The restriction has been removed in Fortran 90. 1.35 Tab to a continuation line. Tabs are not part of the ANSI Fortran definition. They are however easily removable if used only to code lines and for indentation. An obsolescent feature with essentially undefined behaviour.
Some compilers get it wrong.
These depend on the character set of the host. An obsolescent feature legendary for producing unreadable code. An obsolescent feature legendary for producing unreadable code. An obsolescent feature which makes enhancement more difficult. 1.43 Shared DO termination for nested DO loops.