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Referring to the Base and Current Frames

It is often necessary to refer to the base and current Frames (§13.4) within a FrameSetFrameSet, but it can be cumbersome having to obtain their indices from the BaseBase and CurrentCurrent attributes on each occasion. To make this easier, two macros, AST__BASE and AST__CURRENT, are defined in the “ast.h” header file and may be used to represent the indices of the base and current Frames respectively. They may be used whenever a FrameFrame index is required.

For example, when adding a new Frame to a FrameSet (§13.3), you could use the following to indicate that the new Frame is related to the existing current Frame, whatever its index happens to be:

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Of course, the Frame you added would then become the new current Frame.