mnemonics for /dual flags

This falls in the category of noise or trivia, but I found it interesting.

Did you know that the /dual regex flags have not just two but four 
possible spellings for real words?  The fourth was wholly unknown to me.

    1. dual  /ˈdjuːəl/
        MEANING:   two-fold, double
        ETYMOLOGY: < Latin duāl-is containing two, < du-o two
        URL: http://www.oed.com:80/Entry/58110

    2. laud  /lɔːd/
        MEANING:   praise, high commendation
        ETYMOLOGY: < Old French laude, < Latin laud-em, laus praise.
        URL: http://www.oed.com:80/Entry/106223

    3. auld  /ɔːld/ Sc. /ɑːld/  
        MEANING: = old adj.; as in auld lang-syne, ‘old long-since,’ old long-ago            
            (used subst.); Auld Reekie, ‘Old Smoky,’ a sobriquet of Edinburgh;
            auldfarrand, ‘favouring,’ i.e.  resembling the old or adult, having
            the manners or sagacity of age; auld-warld, old-world.
        ETYMOLOGY: mod. Scots and north English descendant of
            Old English ald, which became in midl. dialect in
            13th cent. old n.²
        URL: http://www.oed.com:80/Entry/13130

    4. udal  /ˈjuːdəl/
        MEANING: udal land n. (also udal lands) land(s) in Orkney or Shetland
            held by the old native form of freehold tenure; also, Land
            held in absolute ownership without service or acknowledgement
            of any superior.
        ETYMOLOGY: Orkney and Shetland form of Norwegian odal, odel, Old Norse
            óðal property held by inheritance (Norwegian odal n., Swedish odal,
            Danish odel now adj. and in comb.) = Old High German uodal, also uodil,
            Old Saxon óđil, Old English œ́ðel, éðel, < root að, ôð, whence also Old
            High German adal, German adel noble descent, Old High German ędili,
            German edel, Old English æðele, eðele noble.
        URL: http://www.oed.com:80/Entry/208526

--tom

• mnemonics for /dual flags by Tom Christiansen