This is temporary : how transient projects are redefining architecture / edited by: Cate St Hill. (OCLC #919342602)

For this record, it was tempting to add a full stop following St in the author’s name, although it does not appear that way anywhere on the book, or on the author’s web site. We often do that in American English when words are abbreviated, as in St. Louis, or Mr. Mom. However, in British English when the shortened word is more of a contraction (say, the first and last letter) instead of an abbreviation (the first couple of letters), no full stop is used; for example: Mr for Mister, Dr for Doctor, St for Saint, but still Wed. for Wednesday.

The editor of this title is based in London, which may explain the punctuation used on this piece, and I transcribed that to the record:

    245 00 ǂa This is temporary : ǂb how transient projects
        are redefining architecture / ǂc edited by: Cate St Hill.
    700 1_ ǂa St Hill, Cate, ǂe editor.

my-life-as-a-pre-librarian replied to your post: For honor, glory & union : th…

Could you put in a 246 with no abbreviations? Just curious 🙂

Good question! Yes, I think that would be fine.

The LC-PCC PS for RDA specifically recommends recording a variant title substituting the corresponding spelled-out form of the abbreviation (if it is thought that some catalog users might reasonably expect that the form was spelled out in the source) if the abbreviation occurs as one of the first five words of the Title proper.

Though these particular abbreviations appear later in the title, you could justify the 246 with the main instruction, which says “record variant titles that are considered important for identification or access”:

246 3_ ǂa For honor, glory & union : ǂb the Mexican and
    Civil War letters of Brigadier General William Haines Lytle