## Changes Introduced in V7.1.1

The following describes the most significant changes which occurred in the AST library between versions V7.1.0 and V7.1.1:

1. When a FitsChanFitsChan is used to write an “offset” SkyFrameSkyFrame (see attribute SkyRefIsSkyRefIs) to a FITS-WCS encoded header, two alternate axis descriptions are now created - one for the offset coordinates and one for the absolute coordinates. If such a header is subsequently read back into AST, the original offset SkyFrame is recreated.

2. A bug has been fixed in FitsChan that caused inappropriate CTYPE values to be generated when writing a FrameSetFrameSet to FITS-WCS headers if the current FrameFrame describes generalised spherical coordinates (i.e. a SkyFrame with SystemSystem=Unknown).