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I came across a strange symbol while reading the report on the ALGOL 58 programming language (p. 19):

Form: Δ ~ procedure I(Pᵢ) =: I(Pₒ), I(Pᵢ) =: I(Pₒ), SQUIGGLE SQUIGGLE SQUIGGLE, I(Pᵢ) =: I(Pₒ) Δ ; Δ ; SQUIGGLE SQUIGGLE SQUIGGLE ; Δ begin Σ ; Σ ; SQUIGGLE SQUIGGLE SQUIGGLE ; Δ ; Δ ; SQUIGGLE SQUIGGLE SQUIGGLE ; Σ ; Σ end

I am referring to the squiggle that appears repeated three times after some semicolons and commas in the above clipping. It somewhat resembles a tilde ~, but it is clearly a distinct symbol, since a normal tilde appears next to the delta.

Was this mark an ad-hoc invention or is it an established symbol? Does it have a recognisable name? What is its Unicode code point, if one exists?

(I don’t think there is a separate site for typography questions, but I did see that questions about typographical marks seem to be accepted here.)

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    You might do better over on one of the programming or computer science stacks, since it appears to be a symbol that is part of a specific programming notation (it appears to represent items of a subscripted list). – KillingTime Jan 21 at 8:48
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    ﹏ ﹏ ﹏ Wavy low line (U+FE4F). [Graphemica] – Decapitated Soul Jan 21 at 9:01
  • I have vague recollections that this ~~~ represents a list but regret I have no memory of the name for the symbol. – Anton Jan 21 at 10:28
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    The symbol does not appear in List of mathematical symbols by subject or in Glossary of mathematical symbols. I suggest it is a placeholder for more P terms: "P, P, ﹏ ﹏ ﹏, P is the ordered list of actual parameters ..." So a glorified ellipsis. – Weather Vane Jan 21 at 10:55
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    I’m voting to close this question because it's about obscure mathematical symbology, not "use of English" – FumbleFingers Jan 21 at 13:22