What's the origin of term "mat"?

[Jakub Zalewski]

I know that the term "mat" is used to refer to a test in Chez Scheme repository [0].  I also noticed that Swish also uses mat/mats to refer to test/tests [1].  I was wondering about the origin of the term?  Was it an abbreviation for "minimal acceptance test"?

[0] https://github.com/cisco/ChezScheme/blob/main/mats/mat.ss

[1] https://github.com/becls/swish/blob/dev/src/run-mat

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Jakub