It was, but there were exceptions. It turns it that this symbol, in the Chicago font, is mapped to a control code (this is pre-Unicode; fonts were limited to 256 characters, so such creative use wasn’t considered deadly sin)
https://developer.apple.com/library/archive/technotes/te/te_...:
Chicago Control-Q prints propeller or clover symbol
Date Written: 7/4/90
Last reviewed: 6/14/93
How do I get the character that represents the clover used for Command-key equivalents in documents and in menus?
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This key is documented in the Apple Style Guide, which is available on the latest Developer CD Series disc as well as from APDA. One little feature of Key Caps which is not widely known is the Control key (not the Command or Option keys). Pressing the Control key in Chicago shows that Control-Q in Chicago maps to the propeller symbol for which you search. Control-Q generates the character code 17; the standard Macintosh character set (see Inside Macintosh Volume VI, page 12-5) specifies this symbol for it.
Chicago Control-Q prints propeller or clover symbol
Date Written: 7/4/90
Last reviewed: 6/14/93
How do I get the character that represents the clover used for Command-key equivalents in documents and in menus?
___
This key is documented in the Apple Style Guide, which is available on the latest Developer CD Series disc as well as from APDA. One little feature of Key Caps which is not widely known is the Control key (not the Command or Option keys). Pressing the Control key in Chicago shows that Control-Q in Chicago maps to the propeller symbol for which you search. Control-Q generates the character code 17; the standard Macintosh character set (see Inside Macintosh Volume VI, page 12-5) specifies this symbol for it.