How to establish Hilkhot de'ot, pere.k 4 leha-Rambam?.

According to LCRI 25.6A2:  "Although the title of a part title contains a general term that can be abbreviated (e.g., "Preface," "Number *") or contains a general term in a foreign language that has an English equivalent (e.g., "* Band," "Livre *"), give the
term in the exact form that is found in the source used for establishing the uniform title."
The example given is the reverse of that regarding Hilkhot de'ot (full spelling of designator on the piece, warning against abbreviating it in the heading), but the statement in the rule is not ambiguous.

Another question that might arise is, "Doesn't this lead to inconsistency in the headings, if one piece spells out 'perek' and another doesn't?"  My answer to that one is, "Whenever I ask CPSO if an inconsistency bothers them, they say NO."

One might consider bracketing into the 670 the info that the actual work we're talking about is the Mishneh Torah.  I don't think this can be signaled in the references, since the "higher body" of Hilkhot de'ot is "Sefer ha-mada'" (as shown in n  85006506) and there's no need to backtrack even that far the references in your NAR.

100 1  Maimonides, Moses,$d1135-1204.$tHilkhot de'ot.$nP. 4
400 1  Maimonides, Moses,$d1135-1204.$tHilkhot de'ot.$nPere.k 4
670    Hilkhot de'ot p. 4 leha-Rambam, 1925:$bp. 3 (pere.k revi'i [Hilkhot de'ot is 2nd part of Sefer ha-mada' from his Mishneh Torah])