This is a boolean attribute which controls what is returned by the AST_READ function when it is used to read from an StcsChan. If StcsArea is set non-zero (the default), then a Region representing the STC CoordinateArea will be returned by AST_READ. If StcsArea is set to zero, then the STC CoordinateArea will not be returned.

StcsChan

• Other attributes such as StcsCoords and StcsProps can be used to specify other Objects to be returned by AST_READ. If more than one of these attributes is set non-zero, then the actual Object returned by AST_READ will be a KeyMap, containing the requested Objects. In this case, the Region representing the STC CoordinateArea will be stored in the returned KeyMap using the key " AREA" . If StcsArea is the only attribute to be set non-zero, then the Object returned by AST_READ will be the CoordinateArea Region itself.

• The class of Region used to represent the CoordinateArea for each STC-S sub-phrase is determined by the first word in the sub-phrase (the " sub-phrase identifier" ). The individual sub-phrase Regions are combined into a single Prism, which is then simplified using AST_SIMPLIFY to form the returned region.

• Sub-phrases that represent a single value ( that is, have identifiers " Time" , " Position" , " Spectral" or " Redshift" ) are considered to be be part of the STC CoordinateArea component.

• The TimeFrame used to represent a time STC-S sub-phrase will have its TimeOrigin attribute set to the sub-phrase start time. If no start time is specified by the sub-phrase, then the stop time will be used instead. If no stop time is specified by the sub-phrase, then the single time value specified in the sub-phrase will be used instead. Subsequently clearing the TimeOrigin attribute (or setting its value to zero) will cause the TimeFrame to reprsent absolute times.

• The Epoch attribute for the returned Region is set in the same way as the TimeOrigin attribute (see above).