Variable length segments

File-AID for IMS enables you to browse/edit variable length segments the same as fixed length segments, with the following differences:

• Formatted mode:

  • When you browse/edit a variable length segment, the first two characters of data shown are always the contents of the Segment Size field. The segment layout you use for the segment must include the Segment Size field. When in edit mode, you can change the length of the segment by typing directly over the Segment Size field. If you attempt to shorten or lengthen the segment beyond its defined minimum or maximum length, an error is returned. The long message for the error indicates the allowable minimum or maximum length.
  • When the variable length segment you are browsing/editing is a logical child or concatenated segment, the way in which the segment appears on the screen depends on what you specified for the segment in the segment/layout XREF function. If you specified that the segment layout for the logical child contains the logical child’s Destination Parent Concatenated Key (DPCK), the layout should also contain two characters for the Segment Size field (immediately before the DPCK). If the layout you provided does not include the Segment Size field, the size field is associated and displayed with the first two positions of the DPCK. This process also causes the remaining data fields in the segment to be misaligned with the data-names

  Conversely, if the segment/layout XREF specified that the segment layout for the logical child or concatenated segment does not contain the logical child’s DPCK, File-AID for IMS generates both the two-character size field and the DPCK.

  • When the variable length segment you are browsing/editing is a concatenated segment, you can be restricted. If the logical child portion of the concatenated segment is variable length, you cannot browse or edit the segment in this mode. This limitation applies regardless of whether the destination parent portion of the concatenated segment is fixed or variable in length. You can avoid this restriction by making the logical child portion of the segment key-only (enabling you to browse/edit the destination parent portion) or the destination parent portion of the segment key-only (enabling you to browse/edit the logical child portion).
  • You can browse/edit a concatenated segment with a fixed length logical child and variable length destination parent without restriction.
• Unformatted mode:
  • There are no restrictions affecting the browsing/editing of any variable length segment.
  • The segment length line displays the segment’s current length, minimum allowable length, and maximum allowable length. For a concatenated segment, the current, minimum, and maximum lengths are displayed for both the logical child and the destination parent.
  • When editing a variable length segment, you can change the segment’s current length by either typing over the segment length displayed on the segment length line or typing over the two-byte Segment Size field displayed as part of the segment contents. If you type over both, the value in the two-byte Segment Size field overrides the value on the segment length line. After your next keyboard interaction, the segment is expanded/contracted. When you edit a concatenated segment with a variable length logical child and destination parent, you can change their lengths independently of each other.
• Index mode:
  • You can increase the length of a variable length segment by typing data past the current end of the segment. Deleting data from the end of a segment does not decrease its length.
  • You must not increase the length of a concatenated segment, regardless of whether the logical child, destination parent, or both are variable length.
  • You must not type over the two-byte Segment Size field.