Punctuation:

A comma is placed usually at the end of subfield $a, $b, $c, and/or $x if another subfield follows.

Field 510 ends with a hyphen if one is present at the end of subfield $b; otherwise the field does not end with a mark of punctuation, unless the field ends with an abbreviation, initial/letter, or other data that ends with a mark of punctuation.

When the reference note consists of a name/title citation, a period and space follow the author's name.

Example:

510 4#$aStreeter, T.W. Texas,$c997