In a flowchart or process diagram, what is the symbol for a FIFO queue?

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3 Answers

I don't know if this is canonical but, does this count?

Also here are examples of queues in SDL-88

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A stack is typically represented on a blackboard like this:

Reason being, you want the diagram to show "there's only 1 way in, one way out", and it's LIFO

For a queue, I would use something like this:

Shows there's both an entry and an exit, and that it is FIFO

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I don't have a source to cite, unfortunately, but I recall seeing it represented as an isosceles trapezoid.

Actually I found an example of it here (though maybe not the most authoritative of sources).

Edit: From comments it looks like the example site I had linked is no longer available. This is a recreation of what was in the original document:

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