19 Reading and writing STC-S descriptions (StcsChans)

The ?? class provides facilities for reading and writing IVOA “STC-S” descriptions. STC-S (see http://www.ivoa.net/Documents/latest/STC-S.html) is a linear string syntax that allows simple specification of the STC metadata describing a region in an astronomical coordinate system. AST supports a subset of the STC-S specification, allowing an STC-S description of a region within an AST-supported astronomical coordinate system to be converted into an equivalent AST ?? object, and vice-versa. For further details, see the full description of the StcsChan class in Appendix D.