## Changes Introduced in V3.5

The following describes the most significant changes which have occurred in the AST library between versions V3.4 and V3.5:

1. AST now provides facilities for representing regions of various shapes within a coordinate system. The RegionRegion class provides general facilities which are independent of the specific shape of region being used. Various sub-classes of Region are also now available which provide means of creating Regions of specific shape. Facilities provided by the Region class include testing points to see if they are inside the Region, testing two Regions for overlap, transforming Regions from one coordinate system to another etc.

2. A new class of 1-dimensional FrameFrame called FluxFrameFluxFrame has been added which can be used to describe various systems for describing ovserved value at a single fixed spectral position.

3. A new class of 2-dimensional Frame called SpecFluxFrameSpecFluxFrame has been added which can be used to describe a 2-d frame spanned by a spectral position axis and and an observed value axis.

4. A new class of MappingMapping called RateMapRateMap has been added. A RateMap encapsulates a previously created Mapping. The inputs of the RateMap correspond to the inputs of the encapsulated Mapping. All RateMaps have just a single output which correspond to the rate of change of a specified output of the encapsulated Mapping with respect to a specified input.

5. The SkyFrameSkyFrame class now supports a value of “J2000” for SystemSystem. This system is an equatorial system based on the mean dynamical equator and equinox at J2000, and differs slightly from an FK5(J2000) system.

6. A new class called KeyMapKeyMap has been added. A KeyMap can be used to store a collection of vector or scalar values or Objects, indexed by a character string rather than an integer.

7. The parameter list for the astRateastRate method of the Mapping class has been modified. It no longer returns a second derivative estimate. Existing code which uses this method will need to be changed.

8. Methods (astSetFits<X>) have been added to the FitsChanFitsChan class to allow values for named keywords to be changed or added.