I would interpret what it states in the LC-PCC PS to mean just that -- if information in a field ends in a closing parens mark of punctuation then no period is needed or should be added. 

As a long-time maps cataloger I can also state that there has been in place for decades the "practice" of ending the 255 field with a period even when a coordinates statement that ends with a closing parens is present. My assumption is that the data in 255 $c is considered something like a "phrase" outlining the bounding box or point coordinates for a given geographic area and the parentheses serve not as true punctuation marks but as a means to encircle that data and keep it together in one place, hence ending that field in ")." has always been done.

Paige Andrew

Cartographic Resources Cataloging Librarian

Penn State Libraries

From: Program for Cooperative Cataloging <[log in to unmask]> on behalf of Yang Wang <[log in to unmask]>
Sent: Friday, July 19, 2019 1:19 PM
To: [log in to unmask]
Subject: [PCCLIST] Ending mark of punctuation in 830

Per  LC-PCC PS for (RDA), a right parenthesis “)” is an ending mark of punctuation. So, in the following example in OCLC’s Support & Training—Bib Formats and Standards (https://www.oclc.org/bibformats/en/8xx/830.html),



the final punctuation (period) seems to be unnessary. But in OCLC’s bib file, it is not uncommon to see 830 fields end like that. Is it an old practice?