## Changes Introduced in V5.3

The following describes the most significant changes which occurred in the AST library between versions V5.2 and V5.3:

1. The details of how a FrameFrame is aligned with another Frame by the astFindFrameastFindFrame and astConvertastConvert functions have been changed. The changes mean that a Frame can now be aligned with an instance of a sub-class of Frame, so long as the number of axes and the DomainDomain values are consistent. For instance, a basic 2-dimensional Frame with Domain “SKY” will now align succesfully with a SkyFrameSkyFrame, conversion between the two Frames being achieved using a UnitMapUnitMap.

2. The arrays that supply input values for astMapPut1<X> are now declared “const”.

3. Added method astMatchAxesastMatchAxes to the Frame class. This method allows corresponding axes within two Frames to be identified.

4. The astAddFrameastAddFrame method can now be used to append one or more axes to all Frames in a FrameSetFrameSet.