I'm a bit confused with determining how to deal with 130s/240s for collections of popular music, whether needed to break a conflict, or to comply with other RDA/LC-PCC PS instructions. Below are a few examples I've come across in the volumes I'm working with today: Part of the confusion concerns RDA 184.108.40.206.3 (conventional collective titles) and associated LC-PCC PS (LC practice); also with 220.127.116.11 (Additions to Access Points Representing Musical Works with Distinctive Titles).
Single composer, collection of random songs (or "best of"):
9781480393752 (Best of John Legend): All of the songs appear to be composed by John Legend, either alone or in addition to others; John appears to be the 1st named in each of the pieces. Following LC practice on 18.104.22.168.3 would seem to call for a 240 Songs.$kSelections (and 700 12$iContainer of (work):$aLegend, John.$tAll of me; though that part of the PS seems to be followed less frequently).
A semi-related question, also related to the recent discussion, "Parentheses or separate subfield for dates in "Selections" AAPs?": When using 240$a[Songs/Poems/whatever].$kSelections, or when is it necessary to break the conflict with other $a[whatever].$kSelections? For example, would ISBN 9781480360617 (Bruno Mars; Hal Leonard piano play-along) and 9781480394988 (Bruno Mars; Hal Leonard guitar play-along) both have the same 240, "Songs.$kSelections", or would it be required (if one were contributing these as BIBCO records, and/or cataloging according to LC practice) to add something to the 240 to differentiate the piano play-along from the guitar play-along? In December 2013 and March 14, there was some discussion of this, including a post from Dave Reser  about LC re-thinking the implementation of the 22.214.171.124 instructions. Has anything developed since then?
Single composer, collection of songs from specific "album" (or other similar-type-of-thing with a distinctive title):
9781495001970 (X : piano/vocal/guitar / Ed Sheeran)
In this case, the songs appear to be from a specific album rather than just a collection of random selections. Should the 240, required to break the conflict (with the sound recording of X, and potentially with other expressions of X for other instrumentations) be Songs.$kSelections, or would it be $aX,$mvoice, piano, guitar, perhaps based on that having become the title by which that collection of songs has become known?
On "piano/vocal/guitar": I sent a message to MLA-L on Thu, 30 Oct 2014 10:10:52 -0500, subject "250 vs.500 or 245b for "Piano. Vocal. Guitar"-like statements,"  which led to some discussion of how this type of statement should appear, but there didn't appear to be a clear answer as to the proper way to treat it.
Multiple composers, based on single performer's "album":
9781480384590 (20 greatest hits / Aretha Franklin.)
130 $a20 greatest hits,$mvoice, piano, guitar.
In this case, "Aretha Franklin" appears above "20 greatest hits"; it's not clear to me whether the 245 should be "20 greatest hits / Aretha Franklin", as it is in the OCLC record (currently an AACR2 record with 100 Franklin main entry), or "Aretha Franklin, 20 greatest hits" (which, if not the 245, I would add as a 246). Some of the songs may include Aretha as the composer, but most are by other composers, resulting in title-based primary access point.
For the 130, 126.96.36.199 seems applicable, and (if the 245 remains as-is) "$a20 greatest hits,$mvoice, piano, guitar" could be a validly constructed string, but it seems like Aretha Franklin should be mentioned in the 130 in some way, given that "20 greatest hits" is a bit generic. So, should the 245 be changed to move Aretha from $c to $a? In that case, there doesn't appear to currently be a conflict, so no 130 would be needed.
 (unfortunately requires login to view archives, but should be available for subscribers): https://list.indiana.edu/sympa/arc/mla-l/2014-10/msg00287.html
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