And thanks to Mark as well, and to all others who may respond.  It's very helpful.

Michael S. Borries
Cataloger, City University of New York
151 East 25th Street, 5th Floor
New York, NY  10010
Phone: (646) 312-1687
Email: [log in to unmask]

-----Original Message-----
From: Program for Cooperative Cataloging [mailto:[log in to unmask]] On Behalf Of Ehlert, Mark K.
Sent: Monday, March 20, 2017 2:40 PM
To: [log in to unmask]
Subject: Re: [PCCLIST] Question about use of RDA relators in authority records

From: Program for Cooperative Cataloging [mailto:[log in to unmask]] On Behalf Of Michael Borries
Sent: Monday, March 20, 2017 1:24 PM
> I know I should know this, so apologize for taking up people's time, 
> but is it considered best practice now to use relators in MARC 500 
> fields, rather than the field by itself, or is this a matter of 
> cataloger's judgment?  I don't recall seeing a policy statement here, but since I am something of a "jack-of-all-trades"
> here, I often miss things, and I seem to see records done both ways.

According to DCM Z1, 5XX See Also From Tracing - General Information:

"LC/PCC catalogers applying RDA instructions may use subfield $i in conjunction with subfield $w code 'r' for relationship designators.  When applying RDA relationship designators in 5XXs, supply terms from Appendix I, J or K; capitalize the initial letter of the term and follow the term with a colon.

"Until a decision is reached by the PCC Policy Committee on the use of relationship designators in authority records, LC/PCC catalogers may continue to use the subfield $w codes "a" (earlier) and "b" (later) or optionally use the appropriate relationship designators from Appendix K to provide relationship links between corporate entities (510 or 511)."

Mark K. Ehlert                 O'Shaughnessy-Frey Library
Cataloging and Metadata        University of St. Thomas
  Librarian                    2115 Summit Avenue
Phone: 651-962-5488            St. Paul, MN 55105

  "Experience is by industry achieved // And perfected by the swift course of time"--Shakespeare, "Two Gentlemen of Verona," Act I, Scene iii