why is maximum single-line length limited to 132 characters in Fortran Standard?

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Is it about performance, clean source code, compilers, ...? I know that many compilers allow longer single-line codes. But, if this extension is possible without any compromise, then why does Fortran standard strictly adhere to this rule?

I know that this is very general question (stackoverflow warns me that this question might be downvoted given its title), but I cannot find any resources that explain the logic behind a max length of 132 characters in modern Fortran standard.

Update Oct 22, 2019: See https://j3-fortran.org/doc/year/19/19-138r1.txt for a proposal accepted as a work item for the next 202X revision of the Fortran standard, which eliminates the maximum line length and continuation limits.

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5 Answers

The first programming language I learned back in the 1980s was Fortran (FORTRAN77 to be exact) Everybody was super excited because my group of students were the first ones allowed to use the brand new terminals that had just been set up in the room next to the computer. BTW: The computer was an IBM mainframe and it resided in a room the size of a small concert hall, about four times the size of the classroom with the 16 terminals. I remember having more than once spent hours and hours debugging my code only to find out that in one of my code lines I had again been using the full line width of 80 characters that the terminal provided instead of the 72 characters allowed by Fortan77. I used to call the language Fortran72 because of that restriction. When I asked my tutor for the reason he pointed me to the stack of cardboard boxes in the hallway. It was rather a wall of boxes, 8m long and almost 2m high. All these boxes were full of unused punch cards that they did not need anymore after the installation of the terminals. And yes the punchcards only used 72 characters per code line because the remaining 8 were required for the sequence number of the card. (Imagine dropping a stack of cards with no sequence numbers punched in.)

I am aware that I broke some rules and conventions here: I hope you still like that little piece of trivia and won't mind that my story does not exactly answer the original question. And yeah, it also repeats some information from previous answers.

user_63939030

The reason was sequence numbers punched in columns 73-80 of the source code cards. When you dropped your program deck on the floor, they allowed you to bring the scrambled deck to a sorting machine (a large 5 foot long stand alone machine) and sort the deck back into order.

A sequencer program read the deck and could punch a new deck with updated sequence numbers, so the programmer did not get involved in the numbering. You punched a new deck after every few dozen changes. I did it many times 1970-1990.

user_136942400
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