## Changes Introduced in V5.0

The following describes the most significant changes which occurred in the AST library between versions V4.6 and V5.0:

1. The AST library is now thread-safe (assuming that the POSIX pthreads library is available when AST is built). Many of the macros defined in the ast.h header file have changed. It is therefore necessary to re-compile all source code that includes ast.h.

2. New methods astLockastLock and astUnlockastUnlock allow an AST ObjectObject to be locked for exclusive use by a thread.

3. The TimeFrameTimeFrame class now support Local Time as a time scale. The offset from UTC to Local Time is specified by a new TimeFrame attribute called LTOffsetLTOffset.

4. The ChannelChannel class has a new attribute called StrictStrict which controls whether or not to report an error if unexpected data items are found within an AST Object description read from an external data source. Note, the default behaviour is now not to report such errors. This differs from previous versions of AST which always reported an error is unexpected input items were encountered.