The in-out part affects the processing of simple string literals appearing in the editing specifications. If the in-out part of a FORMAT declaration is designated as OUT or unspecified (in which case OUT is assumed), simple string literals appearing in the editing specifications of the format are read-only. If the in-out part is designated as IN, such simple string literals are read-write. For more information, refer to “Simple String Literal” later in this section.

<in-out part>

──┬───────┬────────────────────────────────────────────────────────────┤
  ├─ IN ──┤
  └─ OUT ─┘