Close the current graphic segment and open a new graphic segment with the current plotting attributes selected by PENCIL. All the commands of GREG open at least one new segment, but the immediate routines do not. This routine must be called prior to calling a series of immediate routines to ensure that the plot will appear with the currently selected graphic attributes, and to allow a selective erasure of the plot. NAME is a character string indicating the desired name of the segment, and ERROR a logical error flag. All plot request issued between two successive calls to GR_SEGM will make a single graphic segment. Note however that every GREG command having an effective plot action creates one or more graphic segments.