Editing Global variable (section)

==Global-only and global-by-default==

A number of non-[[structured programming|structured]] languages, such as (early versions of) [[BASIC]], [[COBOL]] and [[Fortran]] I (1956) only provide global variables. Fortran II (1958) introduced subroutines with local variables, and the COMMON keyword for accessing global variables.  Usage of COMMON in FORTRAN continued in FORTRAN 77,<ref>{{cite web|url=https://web.stanford.edu/class/me200c/tutorial_77/13_common.html|title=Fortran 77 Tutorial}}</ref> and influenced later languages such as PL/SQL.  Named COMMON groups for globals behave somewhat like structured namespaces.<ref>{{cite web|url=http://www-numi.fnal.gov/offline_software/srt_public_context/WebDocs/Companion/first_steps/stack_and_heap.html|title=First Steps: Stack & Heap Objects}}</ref> Variables are also global by default in [[Forth (programming language)|Forth]], [[Lua (programming language)|Lua]], [[Perl]], and most shells.