## Changes Introduced in V8.4

The following describes the most significant changes which occurred in the AST library between versions V8.3.0 and V8.4.0:

1. The PAL library files included in the AST distribution have been updated to PAL version 0.9.7.

2. Multiple identical NormMaps in series will now be simplified to a single NormMapNormMap.

3. A NormMap that encapsulates a basic FrameFrame will now be simplified to a UnitMapUnitMap.

4. The astTimeAddastTimeAdd method of the TimeMapTimeMap class now include an extra argument that gives the number of values supplied in the arguments array. Note, any existing code that uses this method will need to be changed.

5. The astSlaAddastSlaAdd method of the SlaMapSlaMap class now include an extra argument that gives the number of values supplied in the arguments array. Note, any existing code that uses this method will need to be changed.

6. The astSpecAddastSpecAdd method of the SpecMapSpecMap class now include an extra argument that gives the number of values supplied in the arguments array. Note, any existing code that uses this method will need to be changed.

7. Multiple identical NormMaps in series will now be simplified to a single NormMap.

8. A NormMap that encapsulates a basic Frame will now be simplified to a UnitMap.

9. If the astMapRegionastMapRegion method is used to map a RegionRegion into a new Frame that has fewer axes than the original Region, and if the inverse transformation of the supplied MappingMapping does not specify a value for the missing axes, then those axes are removed entirely from the Region. Previously they were retained, but automatically supplied with bad values. This affects the number of mesh points per axes for such Regions, and so affects the accuracy of overlap determination.