HP Fortran Programmer's Reference (September 2007)

Language elements
Names
Chapter 2 43
Names
In Fortran 90, names denote entities such as variables, procedures, derived types, named
constants, and COMMON blocks. A name must start with a letter but can consist of any
combination of letters, digits, and underscore (_) characters. As an extension in HP Fortran,
the dollar sign may also be used in a name, but not as the first character.
The Fortran 90 Standard allows a maximum length of 31 characters in a name. In HP Fortran
this limit is extended to 255 characters, and all are significant—that is, two names that differ
only in their 255th character are treated as distinct. Names and keywords are case
insensitive: for example, Title$23_Name and TITLE$23_NAME are the same name.
The CASE, IF, and DO constructs can optionally be given names. The construct name appears
before the first statement of the construct, followed by a colon (:). The same name must
appear at the end of the final statement of the construct. For more information about these
constructs, refer to “Control constructs and statement blocks” on page 139.