Keywords: greg-2011

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### New

Any segment opened with `gr_segm` must now be closed with the following new entry point after all the data it contains has been sent to the metacode:

- `gr_segm_close(error)`

The following conditions applies:

- at close time (`gr_segm_close`), a segment is implicitely drawn by `GTV`,
- attempting to send segment data to the metacode while there is no segment currently opened is an error,
- attempting to open (`gr_segm`) a new segment while the previous one is not closed (`gr_segm_close`) is an error,
- attempting to close (`gr_segm_close`) twice a segment is an error.

Given the first point above, the necessity for an `Append` mode for `gtview` is severely reduced. Basically, what you will probably have to do is to replace all the statements `gtview('Append')` by `gr_segm_close(error)`. The only purpose to call `gtview('Append')` is now when you are filling a unique segment, and want the user to see in real-time this segment being filled (e.g. a curve showing the convergence of a computation, or an interactive drawing with the cursor, ...).

Instead of calling `gr_exec('CLEAR SEGMENT FOO')`, programmers can invoke the public subroutine `gt_clear_segment(name,present,error)` where `name` is the segment(s) name to be destroyed (e.g. if `name` is `FOO` it will destroy all the segments named `FOO:*`), `present` is a logical indicating if an error should be raised if no segment with such a name is found, and `error` is an `inout` logical error flag (i.e. it keeps its entering value if no error occurs).

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