Fixed source form

IBM extension begins A fixed source form line is a sequence of 1 to 132 characters. The default line size is 72 characters. This is also the Fortran standard line size. You can change the default using the -qfixed=right_margin compiler option. In XL Fortran there is no limit to the number of continuation lines for a statement, but the statement cannot be longer than 34 000 characters. Fortran 2003 limits the number of continuation lines to 255, while Fortran 95 limits the number of continuation lines to 19.

In fixed source form, columns beyond the right margin are not part of the line and you can use these columns for identification, sequencing, or any other purpose. IBM extension ends

Except within a character context, white space is insignificant. You can embed white space between and within lexical tokens, without affecting the way the compiler treats them.

IBM extension begins Tab formatting means that there is a tab character in columns 1 through 6 of an initial line in XL Fortran, which directs the compiler to interpret the next character as being in column 7. IBM extension ends

Requirements for lines and for items on those lines are:

A comment line begins with a C, c, or an asterisk (*) in column 1, or is all white space. Comments can also follow an exclamation mark (!), except when the exclamation mark is in column 6 or in a character context.
For an initial line without tab formatting:
- Columns 1 through 5 contain either blanks, a statement label, a D or an X in column 1 optionally followed by a statement label.
- Column 6 contains a blank or zero.
- Columns 7 through to the right margin contain statement text, possibly followed by other statements or by an inline comment.
For an initial line with tab formatting in XL Fortran:
- Columns 1 through 6 begin with either blanks, a statement label, or a D or an X in column 1, optionally followed by a statement label. You must follow this with a tab character.
- If you specify the -qxflag=oldtab compiler option, all columns from the column immediately following the tab character through to the right margin contain statement text, possibly followed by other statements and by an inline comment.
- If you do not specify -qxflag=oldtab compiler option, all columns from column 7, which corresponds to the character after the tab, to the right margin contain statement text, possibly followed by other statements and by an inline comment.
For a continuation line:
- Column 1 must not contain C, c, or an asterisk. Columns 1 through 5 must not contain an exclamation mark as the leftmost nonblank character.
  Column 1 can contain a D or an X which signifies a debug line in XL Fortran. Otherwise, these columns can contain any characters allowed in a character context; these characters are ignored.
- Column 6 must contain either a nonzero character or a nonwhite space character. The character in column 6 is the continuation character. Exclamation marks and semicolons are valid continuation characters.
- Columns 7 through to the right margin contain continued statement text, possibly followed by other statements and an inline comment.
- Neither the END statement or a statement whose initial line appears to be a program unit END statement can be continued.

Fortran 2008 begins A semicolon separates statements on a single source line, except when appearing in a character context, in a comment, or in columns 1 through 6. Fortran 2008 ends Two or more semicolon separators that are on the same line and are themselves separated by only white space or other semicolons are considered to be a single separator. A separator that is the last character on a line or before an inline comment is ignored. Statements following a semicolon on the same line cannot be labeled. Additional statements cannot follow a program unit END statement on the same line.