The tab-format source lines are defined as follows: @
A tab in any of columns 1 through 6, or an ampersand in column 1, establishes the line as a tab-format source line.
If the tab is the first nonblank character, the text following the tab is scanned as if it started in column 7.
A comment indicator or a statement number can precede the tab.
Continuation lines are identified by an ampersand (&) in column 1, or a nonzero digit after the first tab.