Selection fields

ISPF uses these CUA-compliant conventions for selection fields:
A single period (.)
Member lists that use a single period in the selection field recognize only a single selection. For example, within the Edit function you see this on your screen:
│EDIT     USER1.PRIVATE.TEST               ROW 00001 of 00002  │
│ Name         VV MM  Created   Changed  Size Init  Mod  ID    │
│ . MEM1       01.00  94/05/12  94/07/22  40    0    0   USER1 │
│ . MEM2       01.00  94/05/12  94/07/22  30    0    0   KEENE │
You can select only one member to edit.
A single underscore (_)
Selection fields marked by a single underscore prompt you to use a slash (/) to select the choice. You may use any nonblank character. For example, the "Panel display CUA mode" field on the ISPF Settings panel has a single underscore for the selection field:
Options
  Enter "/" to select option
  _  Command line at bottom
  _  Panel display CUA mode
  _  Long message in pop-up
Note: In GUI mode, this type of selection field displays as a check box; that is, a square box with associated text that represents a choice. When you select a choice, the check box is filled to indicate that the choice is in effect. You can clear the check box by selecting the choice again.
An underscored field (____)
Member lists or text fields that use underscores in the selection field recognize multiple selections. For example, from the Display Data Set List Option panel, you may select multiple members for print, rename, delete, edit, browse, or view processing.