Table 6.23 — EAs with labels beginning with S
Label Concept definition Figure(s) Attribute value type EQ label Code
SAND_DUNE_ORIENTATION The <<GEODETIC_AZIMUTH>> of the characteristic alignment of a <SAND_DUNE> as caused by the prevailing <WIND>s; sand dune orientation.   REAL PLANE_ANGLE 1181
SATELLITE_NAME The name of a <SATELLITE>.   ENUMERATION   1182
SCND_WEAPON_DEPLOYED_POS-
_CATEGORY		 A category describing the <<SCND_WEAPON_DEPLOYED_POSITION>>.   ENUMERATION   1183
SCND_WEAPON_DEPLOYED_POSITION A number between 0 and 1 inclusive representing the linearly-scaled fractional deployment of the secondary <WEAPON_SYSTEM> of a <MAN_MADE_OBJECT>; secondary weapon deployed position. Zero means fully stowed/retracted and one means fully deployed.   REAL PURE_NUMBER 1184
SCRAP_TYPE The type of scrap.   ENUMERATION   1185
SEA_ICE_TYPE The type of <ICE> in the sea.   ENUMERATION   1186
SEA_NAME The name of a major <WATERBODY> (for example: a <SEA>, a <MARINE_STRAIT>, a <MARINE_GULF>, and/or a <MARINE_BAY>); sea name.   ENUMERATION   1187
SEA_STATE_CATEGORY The roughness of a <WATERBODY_SURFACE> in terms of the Douglas sea-state scale, a <SYSTEM> of categorized mean <WATER_WAVE> heights; sea state category.   ENUMERATION   1188
SEA_STATE_NOISE_POWER_LEVEL The power level of acoustic noise energy in a <WATERBODY> due to <WATER_WAVE>s; sea state noise power level.   REAL PRESSURE_POWER_LEVEL 1189
SEARCH_LIGHT_INTENSITY A number between 0 and 1 inclusive representing the linearly-scaled fractional intensity of moveable external <LIGHTING> that is used to illuminate the environment in arbitrary <DIRECTION>s; search light intensity. Zero means unlit and one means maximum intensity. Search light intensity is also known as spotlight intensity or flashlight intensity.   REAL PURE_NUMBER 1190
SEASON The division of the year (one of four) marked by the passage of the <SUN> through an equinox or solstice; season.   ENUMERATION   1191
SEASONAL_TENT_LOCATION The season in which the <TENT>s of a nomadic people are at a given <LOCATION>.   ENUMERATION   1192
SECCHI_DEPTH The <<DEPTH_BELOW_WATERBODY_SURFACE>> at which a <SECCHI_DISK> disappears from view for an observer located above the <WATERBODY_SURFACE>.   REAL LENGTH 1669
SECONDARY_AERIAL_DEPLOYED-
_POSITION		 A number between 0 and 1 inclusive representing the linearly-scaled fractional deployment of the secondary <AERIAL> on a <MAN_MADE_OBJECT>; secondary aerial deployed position. Zero means fully stowed/retracted and one means fully deployed.   REAL PURE_NUMBER 1193
SECONDARY_AXIS_VELOCITY-
_COMPONENT		 The <<VELOCITY>> component of an <OBJECT> along the secondary axis of a defined spatial reference frame.   REAL SPEED 1194
SECONDARY_BREAKER_AZIMUTH The <<VECTOR_AZIMUTH_GEODETIC>> of a <LINE> drawn perpendicular to the <DIRECTION> of propagation of secondary breaking <WATER_WAVE>s in the wave spectra of a <SURF_ZONE>; secondary breaker azimuth.   REAL PLANE_ANGLE 1195
SECONDARY_BREAKER_RELATIVE-
_ANGLE		 The horizontal angle the secondary breaking <WATER_WAVE>s make with respect to the <BEACH>; secondary breaker relative angle. The value increases from 0 when the <LINE> of the <WATER_WAVE>s parallels the <BEACH>, towards 90 arc degrees on either the right or left flank as seen from <VESSEL>s approaching the <BEACH>.   REAL PLANE_ANGLE 1196
SECONDARY_BROADCAST_FREQUENCY The designated secondary broadcast <<FREQUENCY>> for a communications <DEVICE>.   REAL FREQUENCY 1197
SECONDARY_DOOR_OPEN_POSITION A number between 0 and 1 inclusive representing the linearly-scaled fractional opening of the secondary <DOOR> of a <MAN_MADE_OBJECT>; secondary door open position. Zero means fully closed and one means fully open.   REAL PURE_NUMBER 1198
SECONDARY_MATERIAL-
_CHARACTERISTIC		 The characteristics of the composition of the secondary <MATERIAL> of an <OBJECT>.   ENUMERATION   1199
SECONDARY_MATERIAL_TYPE The type of composition of the secondary <MATERIAL> of an <OBJECT>.   ENUMERATION   1200
SECONDARY_SURFACE_AIR_VELOCITY The <<VELOCITY>> of the <AIR> along the secondary <SURFACE> of an <OBJECT>, generally the bottom, back, or inner side of a layer of <MATERIAL>.   REAL SPEED 1201
SECONDARY_SURFACE_TEMPERATURE The <<TEMPERATURE>> of the medium in contact with the secondary <SURFACE> of an <OBJECT>, generally the top, front, or outer side of a layer of <MATERIAL>; typically used as a boundary condition in thermal solutions.   REAL THERMO_TEMPERATURE 1202
SECONDARY_SURFACE_THERMAL-
_CONDITION		 The physical boundary condition at the secondary <SURFACE> of an <OBJECT>, generally the top, front, or outer side of a layer of <MATERIAL>, that accounts for the thermal interface of an <OBJECT> with the environment at that <SURFACE>; secondary surface thermal condition.   ENUMERATION   1203
SECONDARY_SWELL_WAVE_DIRECTION The <<GEODETIC_AZIMUTH>> of the <DIRECTION> from which secondary <SWELL_WAVE>s are arriving.   REAL PLANE_ANGLE 1204
SECONDARY_SWELL_WAVE_HEIGHT The mean <<HEIGHT>> of the significant (highest one-third) secondary <SWELL_WAVE>s.   REAL LENGTH 1205
SECONDARY_SWELL_WAVE_PERIOD The mean <<TIME_QUANTITY>> that a complete cycle (usually crest to crest or trough to trough) of a secondary <SWELL_WAVE> takes to pass a given fixed point; secondary swell wave period.   REAL TIME 1206
SECONDARY_WAVE_DIRECTION The <<GEODETIC_AZIMUTH>> of the <DIRECTION> from which secondary <WATER_WAVE>s (combined <WIND_WAVE> and <SWELL_WAVE>) in the wave spectra are arriving.   REAL PLANE_ANGLE 1207
SECTOR_DIRECTION The <<GEODETIC_AZIMUTH>> of the <DIRECTION> of an angular sector for which the measurement applies.   REAL PLANE_ANGLE 1208
SECURITY_LEVEL The highest level of security associated with an <OBJECT>.   ENUMERATION   1209
SECURITY_LOCK_TYPE The type of a security lock.   ENUMERATION   1210
SECURITY_SYSTEM_TYPE The type of <SENSOR>s in a security system.   ENUMERATION   1688
SEDIMENT_ATTENUATION-
_FREQUENCY_EXPONENT		 The quantity of <<FREQUENCY>> dependence of the absorption and scattering of acoustic energy as it travels through a <WATERBODY_FLOOR> in <<WATER_DEPTH>>s of 200 metres or less; sediment attenuation frequency exponent.   REAL PURE_NUMBER 1211
SEDIMENT_ATTENUATION_GRADIENT The rate of change with respect to <<DEPTH_BELOW_WATERBODY_FLOOR>> of the distance and frequency gradient of the absorption and scattering of acoustic energy travelling through <SEDIMENT>; sediment attenuation gradient.   REAL POWER_LEVEL_DIFF_LEN_FREQ 1212
SEDIMENT_BASEMENT_REFLECTION-
_COEFFICIENT		 The ratio of reflected acoustic energy to the incident acoustic energy at a <WATERBODY_FLOOR> sediment/basement interface; sediment basement reflection coefficient.   REAL PURE_NUMBER 1213
SEDIMENT_BELOW_LAYERS_DENSITY The density of layers of deep <SEDIMENT>s located below near-surface <SEDIMENT>s on a <WATERBODY_FLOOR>; sediment below layers density.   REAL VOLUMIC_MASS 1214
SEDIMENT_COMP_ATTENUATION The depth and frequency gradient of absorption and scattering of compressional waves while travelling through a layer of <SEDIMENT>; sediment compressional attenuation.   REAL POWER_LEVEL_DIFF_LEN_FREQ 1215
SEDIMENT_COMP_WAVE_SPEED The <<SPEED>> of propagation of compressional waves in a <SEDIMENT>.   REAL SPEED 1216
SEDIMENT_COMP_WAVE_SPEED-
_CURVATURE		 The <<SPEED>> of propagation of compressional waves profile curvature parameter of a layer of <SEDIMENT>; sediment compressional wave speed curvature.   REAL PURE_NUMBER 1217
SEDIMENT_COMP_WAVE_SPEED-
_GRADIENT_TOP		 The rate at which the <<SPEED>> of propagation of compressional waves changes with depth in <SEDIMENT>, evaluated at a water-sediment interface; sediment compressional wave speed gradient top.   REAL RATE 1218
SEDIMENT_CONDUCTIVITY The electrical conductivity of <SEDIMENT> on a <WATERBODY_FLOOR>.   REAL ELECTRIC_CONDUCTIVITY 1219
SEDIMENT_GRAIN_SIZE The negative of the logarithm to the base 2 of the grain diameter of <SEDIMENT> expressed in millimetres; sediment grain size.   REAL PURE_NUMBER 1220
SEDIMENT_LAYER_DENSITY The <<MATERIAL_DENSITY>> of a layer of <SEDIMENT> on a <WATERBODY_FLOOR>.   REAL VOLUMIC_MASS 1221
SEDIMENT_MEAN_BACKGROUND-
_THICKNESS		 The mean background <<THICKNESS>> of the layers of <SEDIMENT> located just below a <WATERBODY_FLOOR>.   REAL LENGTH 1222
SEDIMENT_REFLECTIVITY_ANGLE The angle between a layer of <SEDIMENT> on a <WATERBODY_FLOOR> and a compressional wave that is reflected from it; sediment reflectivity angle.   REAL PLANE_ANGLE 1223
SEDIMENT_SHEAR_ATTENUATION The depth and frequency gradient of absorption and scattering of shear waves while travelling through a layer of <SEDIMENT>; sediment shear attenuation.   REAL POWER_LEVEL_DIFF_LEN_FREQ 1224
SEDIMENT_SHEAR_WAVE_SPEED The <<SPEED>> of propagation of shear waves in a <SEDIMENT>.   REAL SPEED 1225
SEDIMENT_SRF_ATTENUATION The absorption and scattering coefficient of compressional waves travelling through <SEDIMENT> just below a <WATERBODY_FLOOR>; sediment surface attenuation.   REAL POWER_LEVEL_DIFF_LEN_FREQ 1226
SEDIMENT_SRF_ATTENUATION-
_GRADIENT		 The distance and frequency gradient of <<SEDIMENT_SRF_ATTENUATION>>.   REAL GRAD_POWER_LEVEL_DIFF_LEN_FREQ 1227
SEDIMENT_SURFACE_DENSITY The <<MATERIAL_DENSITY>> of the topmost layer of <SEDIMENT> on a <WATERBODY_FLOOR>; sediment surface density.   REAL VOLUMIC_MASS 1228
SEDIMENT_THIN_LAYER_DENSITY The <<MATERIAL_DENSITY>> of a surficial layer of <SEDIMENT> on a <WATERBODY_FLOOR>; sediment thin-layer density.   REAL VOLUMIC_MASS 1229
SEDIMENT_THIN_LAYER_THICKNESS The <<THICKNESS>> of the surficial thin-layer of <SEDIMENT> on a <WATERBODY_FLOOR>.   REAL LENGTH 1230
SEDIMENT_TWO_WAY_TRAVEL_TIME The <<TIME_QUANTITY>> required for compressional waves to travel vertically from a <WATERBODY_FLOOR> to the sediment/basement interface and back to the <SURFACE> of that <WATERBODY_FLOOR>; sediment two-way travel time.   REAL TIME 1231
SEDIMENT_WATER_COMP_WAVE-
_SPEED_RATIO		 The ratio of the <<SPEED>> of compressional waves in a <SEDIMENT> to that in the column of <WATER> above it.   REAL PURE_NUMBER 1232
SENSIBLE_HEAT_FLUX The rate of heat flow between a <PLANETARY_SURFACE> and the <ATMOSPHERE>; sensible heat flux.   REAL IRRADIANCE 1233
SERVICE_BRANCH The branch of a military service or organization.   ENUMERATION   1234
SEVERE_WEATHER_PRESENT An indication that severe weather is present. Severe weather is any atmospheric condition potentially destructive or hazardous to <HUMAN>s.   BOOLEAN   1235
SEWER_TYPE The type of a <SEWER>.   ENUMERATION   1705
SHARP_CURVE_RADIUS The radius of curvature of a <SHARP_CURVE> in a <LAND_TRANSPORTATION_ROUTE>.   REAL LENGTH 1236
SHELTER_BELT An indication that an <OBJECT> (for example: a linear stand of <TREE>s) functions as a shelter belt, protecting other <OBJECT>s from the effects of adverse weather.   BOOLEAN   1237
SHIPPING_NOISE_MEASUREMENT-
_STATUS		 The measurement status of a shipping noise level in a <WATERBODY>, typically taken at 50 hertz.   ENUMERATION   1238
SHIPPING_NOISE_SEASON_TYPE The seasonally adjusted acoustic noise characteristics (for example: spectral class, standard deviation, and/or decibels per octave roll-off) in a <WATERBODY> due to distant shipping; shipping noise season type.   ENUMERATION   1239
SHIPPING_NOISE_SPECTRAL-
_POWER_LEVEL_ROLL_OFF		 The gradient in the shipping noise spectral power level in a <WATERBODY> as a function of <<FREQUENCY>>, typically above 300 hertz; shipping noise spectral power level roll-off.   REAL POWER_LEVEL_DIFF_FREQ_GRADIENT 1240
SHIPPING_NOISE_STD_DEV The standard deviation of shipping noise spectral power level measurements in a <WATERBODY>, typically taken at 50 hertz.   REAL FIELD_OR_POWER_LEVEL_DIFF 1241
SHORELINE_DELINEATED An indication that the delineation of a <SHORELINE> is definite.   BOOLEAN   1242
SHORELINE_PHYSIOGRAPHY The topography and types of <MATERIAL> found on a <SHORE>; shoreline physiography.   ENUMERATION   1243
SHORELINE_TYPE The type of physical characteristics of a <SHORELINE>.   ENUMERATION   1244
SHOWALTER_ATMOSPHERE-
_STABILITY_INDEX		 The degree of stability of the layer of the <ATMOSPHERE> extending from a level near the <PLANETARY_SURFACE> of the <EARTH> to the 500 hectopascals (500 millibar) pressure as calculated by the Showalter method; Showalter atmosphere stability index.   REAL PURE_NUMBER 1245
SIDES_VISIBLE The sides of an <OBJECT> that are visible.   ENUMERATION   1246
SIGMA_COORDINATE_VERTICAL-
_VELOCITY		 The <<WIND_OMEGA>> through a pressure <SURFACE> normalized by the <<ATM_PRESSURE>> at the <PLANETARY_SURFACE> of the <EARTH>; sigma coordinate vertical velocity.   REAL RATE 1247
SIGMA_CROSSWIND_SPREADING_RATE The rate of change per unit time of <<SIGMA_WIDTH_CROSSWIND>>; sigma crosswind spreading rate.   REAL SPEED 1248
SIGMA_DOWNWIND_SPREADING_RATE The rate of change per unit time of <<SIGMA_WIDTH_DOWNWIND>>; sigma downwind spreading rate.   REAL SPEED 1249
SIGMA_VERTICAL_SPREADING_RATE The rate of change per unit time of <<SIGMA_WIDTH_VERTICAL>>; sigma vertical spreading rate.   REAL SPEED 1250
SIGMA_WIDTH_CROSSWIND The horizontal dimension of a <PLUME> or <PUFF> measured in the crosswind dimension between points that are symmetric about the centre of <<MASS>> where 68% of the total <<MASS>> is found; sigma width crosswind.   REAL LENGTH 1251
SIGMA_WIDTH_DOWNWIND The horizontal dimension of a <PLUME> or <PUFF> measured in the downwind dimension between points that are symmetric about the centre of <<MASS>> where 68% of the total <<MASS>> is found; sigma width downwind.   REAL LENGTH 1252
SIGMA_WIDTH_VERTICAL The vertical height of a <PLUME> or <PUFF> measured along the vertical dimension between points that are symmetric about the centre of <<MASS>> where 68% of the total <<MASS>> is found; sigma width vertical.   REAL LENGTH 1253
SIGNAL_LIGHT_CHARACTER A characterization of the signal light emitted by one or more <LIGHT>s at one <LOCATION>. The value is formatted in a Basic Latin string giving the class, number, and colours of flashes or occultations.
EXAMPLES     "Q(6)+L F1", "VQ G", "L F1 (3+2)WR". 		  CONSTRAINED_STRING   1254
SIGNAL_LIGHT_PATTERN The temporal pattern of one complete period of a repeating signal <LIGHT>. The value is formatted in a Basic Latin string as a list of relative duty cycle lengths representing the alternating on and off times of the signal beginning with the length of an ON signal. The duty cycle lengths are expressed as integers separated by commas; spaces are ignored.   CONSTRAINED_STRING   1255
SIGNAL_LIGHT_PATTERN_COUNT The number of flashes/occultations in a group flashing/occulting <<SIGNAL_LIGHT_PATTERN>>; signal light pattern count.   COUNT   1256
SIGNAL_LIGHT_SEQUENCE The specification of the sequence of <<TIME_QUANTITY>>s occupied by intervals of light and dark (eclipse) of a signal <LIGHT>.   STRING   1257
SIGNIF_PRIMARY_BREAKER_HEIGHT The mean <<HEIGHT>> measured from trough to crest of the significant (highest one-third) primary breaking <WATER_WAVE>s in a <SURF_ZONE> wave spectrum; significant primary breaker height.   REAL LENGTH 1258
SIGNIF_SECONDARY_BREAKER-
_HEIGHT		 The mean <<HEIGHT>> measured from trough to crest of the significant (highest one-third) secondary breaking <WATER_WAVE>s in a <SURF_ZONE> wave spectrum; significant secondary breaker height.   REAL LENGTH 1259
SIGNIF_SWELL_WAVE_HEIGHT The mean <<HEIGHT>> measured from trough to crest of the significant (highest one-third) <SWELL_WAVE>s.   REAL LENGTH 1260
SIGNIF_WAVE_HEIGHT The mean <<HEIGHT>> measured from trough to crest of the significant (highest one-third) <WATER_WAVE>s (combined <WIND_WAVE>s and <SWELL_WAVE>s).   REAL LENGTH 1261
SIGNIF_WIND_WAVE_HEIGHT The mean height of the significant (highest one-third) <WIND_WAVE>s, measured from trough to crest.   REAL LENGTH 1262
SINGLE_WHEEL_BEARING_LOAD The estimated load bearing capacity of a <LAND_TRANSPORTATION_ROUTE> for a single wheel of a <GROUND_VEHICLE>.   REAL MASS 1263
SIPLE_PASSEL_WIND_CHILL_INDEX A means of quantifying the combined effect of low <<AIR_TEMPERATURE>> and <<WIND_SPEED>> on the body <<TEMPERATURE>> of <HUMAN>s that may result in hypothermia, expressed as an equivalent <<AIR_TEMPERATURE>> in degrees Celsius given by the formula:
0,0817 · [(5,5488 · V0,5) + 5,81 + (0,5592 · V)] · [T - 33,0] + 33,0
where V is the <<WIND_SPEED>> in metres per second at a <<HEIGHT_AGL>> of 10 metres (approximately 33 feet) and T is the <<AIR_TEMPERATURE>> in degrees Celsius; Siple-Passel Wind Chill Index. 		  REAL THERMO_TEMPERATURE 1264
SKY_GROUND_LUMINANCE_RATIO The ratio of sky luminance to non-sky luminance; sky ground luminance ratio.   REAL PURE_NUMBER 1265
SKY_OBSCURATION_FRACTION A number between 0 and 1 inclusive representing the linearly-scaled fraction of the sky that is covered by <FOG> or other low-altitude atmospheric phenomena, determined at a <PLANETARY_SURFACE>; sky obscuration fraction.   REAL PURE_NUMBER 1266
SLAVED_DECLINATION A fixed value of magnetic variation applied within <EQUIPMENT> functioning as an <AID_TO_NAVIGATION> to the true <DIRECTION> in order to obtain the magnetic values for radials, courses and headings; slaved declination.   REAL PLANE_ANGLE 1267
SMOKE_RATE_FRACTION A number between 0 and 1 inclusive representing the linearly-scaled fraction of the production rate of <SMOKE> by an <OBJECT>. Zero means no <SMOKE> at all and one means maximum production.   REAL PURE_NUMBER 1268
SMOKESTACK_COUNT The number of <SMOKESTACK>s associated with an <OBJECT>; smokestack count.   COUNT   1269
SNOW_ACCUM_DEPTH The <<DEPTH>> of <SNOW_GROUND_COVER> that has accumulated over an <<ACCUMULATION_PERIOD>> or <<ACCUMULATION_PERIOD_CATEGORY>>.   REAL LENGTH 1270
SNOW_ACCUM_DEPTH_EQUIVALENT The <<DEPTH>> of the liquid <WATER> that is equivalent in content to the <SNOW_GROUND_COVER> (not <ICE>) that has accumulated over an <<ACCUMULATION_PERIOD>> or <<ACCUMULATION_PERIOD_CATEGORY>>.   REAL LENGTH 1271
SNOW_AGE The time difference between the reference date and the date of the last measurable <SNOW_PRECIPITATION>; snow age.   REAL TIME 1272
SNOW_DENSITY The density of accumulated <SNOW_PRECIPITATION> on an <OBJECT>.   REAL VOLUMIC_MASS 1273
SNOW_DEPTH_CATEGORY A category describing the <<SNOW_ONLY_DEPTH>>.   ENUMERATION   1274
SNOW_DRIFT_HEIGHT The maximum <<HEIGHT>> of drifts of <SNOW_GROUND_COVER> within a specified <PLANETARY_SURFACE_REGION>.   REAL LENGTH 1275
SNOW_MELTING_RATE The melting rate of <SNOW_GROUND_COVER> as measured by <<SNOW_ONLY_DEPTH>>.   REAL SPEED 1276
SNOW_ONLY_DEPTH The depth of the <SNOW_GROUND_COVER> that may be over <TERRAIN>, <TERRAIN> covered by <ICE>, or floating <ICE>; snow only depth.   REAL LENGTH 1277
SOIL_COMPRESSIONAL_VELOCITY The <<VELOCITY>> of displacement of <SOIL> in the same <DIRECTION> as the compressional (density) wave through that <SOIL> (VP); soil compressional velocity.   REAL SPEED 1278
SOIL_CONE_INDEX The force per unit basal area required to push a cone penetrometer through an increment of <SOIL>; soil cone index. Soil cone index is typically measured at depths from 0,0 to 0,6 metres.   REAL PRESSURE 1279
SOIL_DENSITY_DRY The mean <<MATERIAL_DENSITY>> of the <SOIL>, between the <SURFACE> of the <TERRAIN> and the <BEDROCK>, after it has been dried to a constant <<MASS>> at 378,15 kelvin (105 degrees Celsius).   REAL VOLUMIC_MASS 1280
SOIL_DEPTH The <<DEPTH>> of <SOIL> or unconsolidated <MATERIAL> from the <SURFACE> of the <TERRAIN> to <BEDROCK>.   REAL LENGTH 1281
SOIL_LAYER_DEPTH The <<DEPTH>> of the top of a layer of <SOIL> measured from the <SURFACE> of the <TERRAIN>.   REAL LENGTH 1282
SOIL_MOISTURE_MASS_LOWER_LAYER The <<MASS>> of <WATER> contained between <<SOIL_LAYER_DEPTH>> 5 and <<SOIL_LAYER_DEPTH>> 100 centimetres; soil moisture mass lower layer.   REAL MASS_FRACTION 1283
SOIL_MOISTURE_MASS_TOP_LAYER The <<MASS>> of <WATER> contained between <<SOIL_LAYER_DEPTH>> 0 and <<SOIL_LAYER_DEPTH>> 5 centimetres below the <SURFACE> of the <TERRAIN>; soil moisture mass top layer.   REAL MASS_FRACTION 1284
SOIL_SEISMIC_ABSORPTION-
_COEFFICIENT		 The coefficient in an exponential model of attenuation of seismic waves by <SOIL>; soil seismic absorption coefficient. If A and A0 are resultant and initial amplitudes, respectively, at a given <<FREQUENCY>>, x the distance travelled and a the soil seismic absorption coefficient, they are related by the equation:
A = A0 · exp(-ax). 		  REAL PURE_NUMBER 1285
SOIL_SHEAR_VELOCITY The <<VELOCITY>> of displacement of <SOIL> in the <DIRECTION> perpendicular to the compressional (density) wave through that <SOIL> (VS); soil shear velocity.   REAL SPEED 1286
SOIL_SURFACE_TEMPERATURE The <<TEMPERATURE>> of the <SOIL> at the <SURFACE> of the <TERRAIN>.   REAL THERMO_TEMPERATURE 1287
SOIL_TYPE_USCS The USCS type of the <SOIL>.   ENUMERATION   1288
SOIL_WATER_MASS The <WATER> lost from the <SOIL> upon drying to constant <<MASS>> at 378,15 kelvin (105 degrees Celsius); soil water mass. The value is expressed as the fractional <<MASS>> of <WATER> per unit <<MASS>> of wet <SOIL>.   REAL MASS_FRACTION 1289
SOIL_WATER_VOLUME The <WATER> lost from the <SOIL> upon drying to constant <<MASS>> at 378,15 kelvin (105 degrees Celsius); soil water volume. The value is expressed as the fractional <<VOLUME>> of <WATER> per unit bulk <<VOLUME>> of wet <SOIL>.   REAL VOLUME_FRACTION 1290
SOIL_WETNESS_CATEGORY A category describing the content of liquid and solid <WATER> in the <SOIL> of a <TERRAIN_SURFACE_REGION>; soil wetness category.   ENUMERATION   1291
SOLAR_DIFFUSE_IRRADIANCE The diffuse solar incident flux per unit <<AREA>> of the <SURFACE> of an <OBJECT>; solar diffuse irradiance.   REAL IRRADIANCE 1292
SOLAR_DIRECT_IRRADIANCE The direct solar incident flux per unit <<AREA>> of the <SURFACE> of an <OBJECT>; solar direct irradiance.   REAL IRRADIANCE 1293
SOLAR_RADIANCE_AZIMUTH-
_GEODETIC		 The solar <<INCIDENCE_AZIMUTH_GEODETIC>>; solar radiance azimuth geodetic.   REAL PLANE_ANGLE 1294
SOLAR_RADIANCE_AZIMUTH_LOCAL The solar <<INCIDENCE_AZIMUTH_LOCAL>>; solar radiance azimuth local.   REAL PLANE_ANGLE 1295
SOLAR_RADIANCE_AZIMUTH-
_MAGNETIC		 The solar <<INCIDENCE_AZIMUTH_MAGNETIC>>; solar radiance azimuth magnetic.   REAL PLANE_ANGLE 1296
SOLAR_RADIANCE_ELEV_ANGLE-
_HORIZONTAL		 The solar <<INCIDENCE_ELEV_ANGLE_HORIZONTAL>>; solar radiance elevation angle horizontal.   REAL PLANE_ANGLE 1297
SOLAR_RADIANCE_ELEV_ANGLE-
_LOCAL		 The solar <<INCIDENCE_ELEV_ANGLE_LOCAL>>; solar radiance elevation angle local.   REAL PLANE_ANGLE 1298
SOLAR_RADIATION_CUMULATIVE The rate of solar radiation received over a twenty-four hour <<TIME_QUANTITY>>; solar radiation cumulative.   REAL IRRADIANCE 1299
SONAR_CONFIRMATION An indication that the presence of an <OBJECT> has been confirmed by sonar.   BOOLEAN   1300
SONIC_LAYER_DEPTH The depth of the layer near a <WATERBODY_SURFACE> into which sound rays are trapped by upward refraction effects; sonic layer depth.   REAL LENGTH 1301
SOUND_SIGNAL_PRESENT An indication that an audible marine signal is generated by a <MARINE_AID_TO_NAVIGATION>; sound signal present.   BOOLEAN   1302
SOUND_SIGNAL_TYPE The means used to generate an audible marine signal; sound signal type.   ENUMERATION   1303
SOUND_SPEED The <<SPEED>> at which sound passes through a medium, depending on the <<TEMPERATURE>> and other properties of the medium; sound speed.   REAL SPEED 1689
SOUNDING_DATUM_TYPE The type of a <SOUNDING_DATUM>.   ENUMERATION   1304
SOUNDING_EXPOSITION The type of exposition of a <<DEPTH_OF_WATERBODY_FLOOR>> measured by sounding with respect to the surrounding <REGION>.   ENUMERATION   1305
SOUNDING_INFORMATION Additional information about a <<DEPTH_OF_WATERBODY_FLOOR>> measured by sounding.   ENUMERATION   1306
SOUNDING_MEASUREMENT_TECHNIQUE The type of sounding technique and/or method of measurement of a <<DEPTH_OF_WATERBODY_FLOOR>>.   ENUMERATION   1307
SOUNDING_VELOCITY_CORRECTION-
_TYPE		 The type of correction that has been added to or subtracted from a sounding velocity instrument reading to obtain the correct <<DEPTH_OF_WATERBODY_FLOOR>>.   ENUMERATION   1308
SOURCE The source from which the identification of an <OBJECT> was captured or upgraded.   ENUMERATION   1309
SOURCE_DATA_SET_COMPILE_DATE The date a source data set (for example: a <MAP>) was originally compiled. The date is formatted as specified by <<DATE_FORMAT>> or by <<DATE_TIME_FORMAT>>.   CONSTRAINED_STRING   1310
SOURCE_DATA_SET_EDITION The edition of a source data set (for example: a <MAP>).   STRING   1311
SOURCE_DATA_SET_GENERAL-
_INFORMATION		 General information about, and description of conditions within, a source data set (for example: a <MAP>).   STRING   1312
SOURCE_DATA_SET_NAME The name or identification number of the first source data set (for example: a <MAP>).   STRING   1313
SOURCE_DATA_SET_PRINT_DATE The date a source data set (for example: a <MAP>) was last printed. The date is formatted as specified by <<DATE_FORMAT>> or by <<DATE_TIME_FORMAT>>.   CONSTRAINED_STRING   1314
SOURCE_DATA_SET_REVISION_DATE The date a source data set (for example: a <MAP>) was last revised; source data set revision date. The date is formatted as specified by <<DATE_FORMAT>> or by <<DATE_TIME_FORMAT>>.   CONSTRAINED_STRING   1315
SPATIAL_ANGULAR_PRIMARY-
_COORDINATE		 The angular primary axis coordinate value for a defined spatial reference frame.   REAL PLANE_ANGLE 1316
SPATIAL_ANGULAR_SECONDARY-
_COORDINATE		 The angular secondary axis coordinate value for a defined spatial reference frame.   REAL PLANE_ANGLE 1317
SPATIAL_ANGULAR_TERTIARY-
_COORDINATE		 The angular tertiary axis coordinate value for a defined spatial reference frame.   REAL PLANE_ANGLE 1715
SPATIAL_LINEAR_PRIMARY-
_COORDINATE		 The linear primary axis coordinate value for a defined spatial reference frame.   REAL LENGTH 1318
SPATIAL_LINEAR_SECONDARY-
_COORDINATE		 The linear secondary axis coordinate value for a defined spatial reference frame.   REAL LENGTH 1319
SPATIAL_LINEAR_TERTIARY-
_COORDINATE		 The linear tertiary axis coordinate value for a defined spatial reference frame.   REAL LENGTH 1320
SPECIFIC_GRAVITY The ratio of the <<MATERIAL_DENSITY>> of a substance to that of <WATER> at 277,15 kelvin (4 degrees Celsius); specific gravity.   REAL MASS_FRACTION 1321
SPECIFIC_HEAT The quantity of energy required to raise the <<TEMPERATURE>> of a unit <<MASS>> of a <MATERIAL> by one kelvin; specific heat.   REAL SPECIFIC_HEAT_CAPACITY 1322
SPECIFIC_HUMIDITY The ratio of the <<MASS>> of water vapour to the total <<MASS>> of a <<VOLUME>> of moist <AIR>; specific humidity.   REAL MASS_FRACTION 1323
SPEED A measure of the rate of motion of an <OBJECT>; speed.   REAL SPEED 1324
SPERM_WHALE_CATCH_PER_YEAR The number of sperm <WHALE>s caught within a one-year <<TIME_QUANTITY>>; sperm whale catch per year.   COUNT   1325
SPILLING_BREAKER_FRACTION A number between 0 and 1 inclusive representing the linearly-scaled fraction of breaking <WATER_WAVE>s within a delineated <WATERBODY_SURFACE_REGION> that are spilling. Spilling is a breaking process wherein the <WATER_WAVE> peaks up until it is very steep but not vertical; only the top most portion of the <WATER_WAVE> curls over and descends on the forward slope of the advancing <WATER_WAVE> where it then slides down into the trough. This process starts at scattered foci which coalesce until the <WATER_WAVE> becomes an advancing <LINE> of foam. Zero means no breaking <WATER_WAVE>s are spilling and one means all are spilling.   REAL PURE_NUMBER 1326
SPORT_TYPE The type of sport or exercise performed on an <ATHLETIC_FIELD> or <SPORTS_ARENA>.   ENUMERATION   1327
SPOT_ELEVATION_TYPE The type of a <<TERRAIN_ELEVATION>> measurement at a <LOCATION>; spot elevation type.   ENUMERATION   1328
SPRING_TYPE The type of a <SPRING>.   ENUMERATION   1329
STAIR_CONSTRUCTION_TYPE The type of <MATERIAL> and/or techniques used to construct a <STAIR>; stair construction type.   ENUMERATION   1330
STAIR_STYLE The architectural style of a <STAIR>.   ENUMERATION   1331
STANTON_NUMBER A scalar governing the aerodynamic heat transfer coefficient of an <OBJECT>; Stanton number.   REAL PURE_NUMBER 1332
STELLAR_ALPHA_FLUX The stellar flux of alpha <PARTICLE>s.   REAL PARTICLE_FLUX_DENSITY 1333
STELLAR_ELECTRON_FLUX The stellar flux of electrons.   REAL PARTICLE_FLUX_DENSITY 1334
STELLAR_EM_FLUX The stellar electromagnetic flux level.   REAL FLUX_DENSITY 1335
STELLAR_PROTON_FLUX The stellar flux of protons.   REAL PARTICLE_FLUX_DENSITY 1336
STELLAR_RF_FLUX_10r7 The intensity of <STELLAR_FLUX_RADIO_FREQUENCY_EMISSION> at 10,7 centimetre <<WAVELENGTH>> (2,8 gigahertz).   REAL FLUX_DENSITY 1337
STELLAR_RF_NB_MAXIMUM_TIME The time, relative to the beginning of the day (midnight), of the maximum electromagnetic flux of a noise event associated with a <STELLAR_BURST_RADIO_FREQUENCY_EMISSION>.   REAL TIME 1338
STELLAR_RF_NB_MAXIMUM_TIME-
_QUALITY		 The quality of a <<STELLAR_RF_NB_MAXIMUM_TIME>> measurement.   ENUMERATION   1339
STELLAR_RF_NB_MEAN_FLUX The mean electromagnetic flux of a noise event associated with a <STELLAR_BURST_RADIO_FREQUENCY_EMISSION>.   REAL FLUX_DENSITY 1340
STELLAR_RF_NB_MEAN_FLUX-
_QUALITY		 The quality of a <<STELLAR_RF_NB_MEAN_FLUX>> measurement.   ENUMERATION   1341
STELLAR_RF_NB_PEAK_FLUX The peak electromagnetic flux of a noise event associated with a <STELLAR_BURST_RADIO_FREQUENCY_EMISSION>.   REAL FLUX_DENSITY 1342
STELLAR_RF_NB_PEAK_FLUX-
_QUALITY		 The quality of a <<STELLAR_RF_NB_PEAK_FLUX>> measurement.   ENUMERATION   1343
STELLAR_RF_NB_PERIOD The <<TIME_QUANTITY>> of a noise event associated with a <STELLAR_BURST_RADIO_FREQUENCY_EMISSION>; stellar radio frequency noise burst period.   REAL TIME 1344
STELLAR_RF_NB_PERIOD_QUALITY The quality of a <<STELLAR_RF_NB_PERIOD>> measurement.   ENUMERATION   1345
STELLAR_RF_NB_REMARKS A descriptive or explanatory comment (remarks) regarding a noise event associated with a <STELLAR_BURST_RADIO_FREQUENCY_EMISSION>.   STRING   1346
STELLAR_RF_NB_START The starting time, relative to the beginning of the day (midnight), of a noise event associated with a <STELLAR_BURST_RADIO_FREQUENCY_EMISSION>.   REAL TIME 1347
STELLAR_RF_NB_START_QUALITY The quality of a <<STELLAR_RF_NB_START>> measurement.   ENUMERATION   1348
STELLAR_WIND_ION_TEMPERATURE The <<TEMPERATURE>> of ionized <PARTICLE>s in a <STELLAR_WIND>.   REAL THERMO_TEMPERATURE 1349
STELLAR_WIND_PROTON_DENSITY The density of protons in a <STELLAR_WIND>.   REAL VOLUMETRIC_ENTITY_DENSITY 1350
STELLAR_WIND_SPEED The <<SPEED>> of a <STELLAR_WIND>.   REAL SPEED 1351
STELLAR_WIND_SPEED_GSE_X The <<STELLAR_WIND_SPEED>> in the <DIRECTION> of the <SUN> (in the ecliptic plane) and positive towards the <SUN>; stellar wind speed GSE X.   REAL SPEED 1352
STELLAR_WIND_SPEED_GSE_Y The <<STELLAR_WIND_SPEED>> in the ecliptic plane in a <DIRECTION> perpendicular to the <DIRECTION> of the <SUN>, pointing generally opposite to the <DIRECTION> of revolution of the <EARTH> about the <SUN>, and positive in the contra-revolution <DIRECTION>; stellar wind speed GSE Y.   REAL SPEED 1353
STELLAR_WIND_SPEED_GSE_Z The <<STELLAR_WIND_SPEED>> perpendicular to the ecliptic plane and positive towards the <STAR> Polaris; stellar wind speed GSE Z.   REAL SPEED 1354
STELLAR_X_RAY_FLUX_L_BAND The intensity (flux) of stellar x-rays in the L-band (0,1 - 0,8 nanometres <<WAVELENGTH>>).   REAL RADIANT_EXITANCE_RATE 1355
STELLAR_X_RAY_FLUX_S_BAND The intensity (flux) of stellar x-rays in the S-band (0,05 - 0,4 nanometres <<WAVELENGTH>>).   REAL RADIANT_EXITANCE_RATE 1356
STEM_DIAMETER The diameter of the stem/trunk of a <PLANT> measured at a <<HEIGHT_AGL>> of 1,4 metres.   REAL LENGTH 1357
STORAGE_FACILITY_TYPE The type of storage facilities available at or in the near vicinity of an <OBJECT>.   ENUMERATION   1358
STRUCTURAL_PILE_TYPE The type of a <STRUCTURAL_PILE>.   ENUMERATION   1359
STRUCTURE_DENSITY The areal density of <STRUCTURE>s.   REAL AREAL_ENTITY_DENSITY 1360
STRUCTURE_LIGHTING_TYPE The type of <LIGHTING> on or in a <STRUCTURE>.   ENUMERATION   1361
STRUCTURE_PROTECTION_TYPE The type/degree to which a <STRUCTURE> provides protection to itself or its contents by resisting the effects of an explosion, a <MUNITION>, and a natural disaster (for example: a hurricane, a tornado, and/or an earthquake).   ENUMERATION   1362
STRUCTURE_SHAPE The geometric form or configuration of an <OBJECT>; structure shape.   ENUMERATION   1363
SUMMER_CANOPY_COVER_FRACTION A number between 0 and 1 inclusive representing the linearly-scaled fractional canopy cover of <TREE>s during the summer within a delineated <TRACT>. Zero means no cover and one means completely covered.   REAL PURE_NUMBER 1364
SUNRISE_TIME The <<TIME_OF_DAY>> of sunrise. The time of sunrise is defined to occur when the geometric zenith distance of the centre of the <SUN> is 90,8333 arc degrees; that is, the centre of the <SUN> is geometrically 50 arc minutes below a horizontal plane for an observer at MSL with a level, unobstructed eastern horizon under average atmospheric conditions. The upper limb of the <SUN> will then appear to be tangent to the eastern horizon. The 50 arc minute geometric depression of the centre of the <SUN> used for the computations is obtained by adding the mean apparent <<RADIUS>> of the <SUN> (16 arc minutes) to the mean amount of atmospheric refraction at the horizon (34 arc minutes).   CONSTRAINED_STRING   1365
SUNSET_TIME The <<TIME_OF_DAY>> of sunset. The time of sunset is defined to occur when the geometric zenith distance of the centre of the <SUN> is 90,8333 arc degrees; that is, the centre of the <SUN> is geometrically 50 arc minutes below a horizontal plane for an observer at MSL with a level, unobstructed western horizon under average atmospheric conditions. The upper limb of the <SUN> will then appear to be tangent to the western horizon. The 50 arc minute geometric depression of the centre of the <SUN> used for the computations is obtained by adding the mean apparent <<RADIUS>> of the <SUN> (16 arc minutes) to the mean amount of atmospheric refraction at the horizon (34 arc minutes).   CONSTRAINED_STRING   1366
SUNSHINE_OBSERVATION_PERIOD The <<TIME_QUANTITY>> over which an observation of solar <<ILLUMINANCE>> was taken; sunshine observation period.   REAL TIME 1367
SUNSHINE_PERIOD The <<TIME_QUANTITY>> that solar irradiation occurred; sunshine period.   REAL TIME 1368
SUNSPOT_NUMBER The number of <SUNSPOT>s observed; sunspot number.   REAL PURE_NUMBER 1369
SUNSPOT_NUMBER_INDEX The total number of <SUNSPOT>s plus ten times the number of <SUNSPOT> groups in a given <<TIME_QUANTITY>>(usually one month); sunspot number index.   REAL PURE_NUMBER 1370
SUPERELEVATION The lateral slope (rise/run) of a <LAND_TRANSPORTATION_ROUTE>; superelevation.   REAL PURE_NUMBER 1371
SUPERTANKER_DENSITY The areal density of supertanker <WATER_SURFACE_VESSEL>s. A supertanker <WATER_SURFACE_VESSEL> is characterized by a dead weight greater than 318 000 kilograms (approximately 350 000 tons) and a <<LENGTH>> greater than 325 metres).   REAL AREAL_ENTITY_DENSITY 1372
SURFACE_ANGLE The maximum angle between the <SURFACE> of an <OBJECT> and a perpendicular to the local gravity vector. The value is selected to be between 0 and 90 arc degrees (or equivalent).   REAL PLANE_ANGLE 1373
SURFACE_BACKSCATTER The negative of the ratio of the flux returned (reflected directly back in the <DIRECTION> of incidence) to the incident flux in decibels of the <SURFACE> of an <OBJECT>; surface backscatter.   REAL FIELD_OR_POWER_LEVEL_DIFF 1374
SURFACE_CATEGORY The category of the <SURFACE> of an <OBJECT>.   ENUMERATION   1375
SURFACE_CHARACTERISTIC_TYPE The principal characteristic type of a <SURFACE>.   ENUMERATION   1376
SURFACE_EM_ABSORPTIVITY The ratio of absorbed to incident electromagnetic flux at a <SURFACE>; surface electromagnetic absorptivity.   REAL FIELD_OR_POWER_LEVEL_DIFF 1377
SURFACE_EM_ABSORPTIVITY_SOLAR The <<SURFACE_EM_ABSORPTIVITY>> of all appreciable solar flux (from about 0,0 to 3,0 micrometres in <<WAVELENGTH>>); if expressed in decibels, the negative of the value is used; surface electromagnetic solar absorptivity.   REAL FIELD_OR_POWER_LEVEL_DIFF 1378
SURFACE_EM_DUCT_HEIGHT The <<HEIGHT_AGL>> of the top of a <SURFACE_BASED_EM_DUCT>.   REAL LENGTH 1379
SURFACE_EM_DUCT_STRENGTH The strength of a <SURFACE_BASED_EM_DUCT> as defined by the difference between the maximum and minimum <<RF_REFRACTIVE_INDEX_MODIFIED>> of a trapping layer.   REAL PURE_NUMBER 1380
SURFACE_MATERIAL_TYPE The composition of the <MATERIAL> of the <SURFACE> of an <OBJECT> excluding internal structural <MATERIAL>s; surface material type.   ENUMERATION   1381
SURFACE_REFLECTIVITY A number between 0 and 1 inclusive representing the ratio of the reflected flux to the incident flux at a <SURFACE>; surface reflectivity. Zero means no reflection and one means total reflection.   REAL PURE_NUMBER 1382
SURFACE_SLIPPERY An indication that a <SURFACE> (for example: wet grass and/or wet clay <SOIL>) is slippery.   BOOLEAN   1383
SURFACE_SLOPE The maximum slope (rise/run) of the <SURFACE> of an <OBJECT>.   REAL PURE_NUMBER 1384
SURFACE_SLOPE_ORIENTATION The <<GEODETIC_AZIMUTH>> of the <DIRECTION> of maximum <<SURFACE_SLOPE>>; surface slope orientation.   REAL PLANE_ANGLE 1385
SURFACE_TEMPERATURE The <<TEMPERATURE>> of a <SURFACE>.   REAL THERMO_TEMPERATURE 1386
SURFACE_THERMAL_INDEX The index used to describe the thermal (radiance) characteristic of a <SURFACE>.   INDEX   1387
SURFACE_THERMAL_MODEL The type of thermal (radiance) model being used to determine the interpretation of the thermal index describing the thermal (radiance) characteristic of a <SURFACE>. That value is used to index one or more thermal model-specific lookup tables in order to predict, display, or analyze thermal signatures.   ENUMERATION   1388
SURFACE_THERMAL_SUNSHADING-
_DOMINANCE		 The degree of dominance of the effect of shading from the <SUN> (in the respective sensor domain) over the thermally derived values; surface thermal sunshading dominance. The values are between 0 and 1 inclusive with zero being minimally and one being maximally (but not necessarily completely) dominant. The exact interpretation of this value is determined by the thermal model being used.   REAL PURE_NUMBER 1389
SURFACE_THERMAL_VISUAL-
_DOMINANCE		 The degree of dominance of the visual texture of an image (in the respective sensor domain) over the thermally derived values; surface thermal visual dominance. The values are between 0 and 1 inclusive with zero being minimally and one being maximally (but not necessarily completely) dominant. The exact interpretation of this value is determined by the thermal model being used.   REAL PURE_NUMBER 1390
SURFACE_WIND_SPEED The <<WIND_SPEED>> 10 metres above a <PLANETARY_SURFACE>.   REAL SPEED 1391
SURFICIAL_DEPTH The estimated general depth of <SOIL> or unconsolidated surficial <MATERIAL>s on the <TERRAIN>.   REAL LENGTH 1392
SURGING_BREAKER_FRACTION A number between 0 and 1 inclusive representing the linearly-scaled fraction of breaking <WATER_WAVE>s within a delineated <WATERBODY_SURFACE_REGION> that are surging. Surging means that the <WATER_WAVE> crest tends to advance faster than the base of the <WATER_WAVE> to suggest the formation of a plunging breaker, however, the <WATER_WAVE> base then advances faster than the crest, the plunging is arrested, and the breaker surges up the <BEACH> as a wall of <WATER> which may, or may not, be white water. Zero means no breaking <WATER_WAVE>s are surging and one means all are surging.   REAL PURE_NUMBER 1393
SURVEILLANCE_WINGED_AIRCRAFT-
_TYPE		 The type of a winged surveillance <AIRCRAFT>.   ENUMERATION   1394
SURVEY_CONTROL_POINT_TYPE The type of a control point established by surveying methods.   ENUMERATION   1395
SURVEY_COVERAGE_QUALITY A general evaluation of the coverage quality of a survey, as a category.   ENUMERATION   1397
SURVEY_END_DATE The end date of a survey. The value is formatted as specified by <<DATE_FORMAT>> or by <<DATE_TIME_FORMAT>>.   CONSTRAINED_STRING   1396
SURVEY_START_DATE The start date of a survey. The value is formatted as specified by <<DATE_FORMAT>> or by <<DATE_TIME_FORMAT>>.   CONSTRAINED_STRING   1398
SUSPENDED_CEILING_DEPTH The <<DEPTH>> of a <ROOM_CEILING> suspended from the <SURFACE> above; suspended ceiling depth.   REAL LENGTH 1399
SYNCHRONIZED An indication that a periodic behaviour of an <OBJECT> is synchronized with that of another <OBJECT>.
EXAMPLE     The members of a <SET> of flashing <LIGHT>s may flash in unison. 		  BOOLEAN   1400
SYSTEM_RELAXATION_TIME The <<TIME_QUANTITY>> required for a <SYSTEM> exposed to some discontinuous change in environment to return to the state it would exhibit after an indefinitely long time; system relaxation time.   REAL TIME 1401

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