This?is?about?R?4.0.2?(or 4.0.1) help?on?'paste'.
End?part?of?the?first?paragraph?in?"Details"?section:
If?the?arguments?are?vectors,?they?are?concatenated?term-by-term?to?give?a?character?vector?result.?Vector?arguments?are?recycled?as?needed,?with?zero-length?arguments?being?recycled?to?'""'?only?if?'recycle0'?is?not?true?_or_?'collapse'?is?not?'NULL'.
I?suggest?removing?"?_or_?'collapse'?is?not?'NULL'".
'collapse' has nothing to do with recycling.
Description of 'recycle0' in "Arguments" section:
'logical' indicating if zero-length character arguments should lead to the zero-length 'character(0)' after the 'sep'-phase (which turns into '""' in the 'collapse'-phase, i.e., when 'collapse' is not 'NULL')
I suggest the explanation to include the term "recycle" or "recycling" like the argument name. For example,
'logical' indicating if "zero-length recycling rule" is in effect, where mix of zero-length and nonzero-length arguments leads to zero-length ...
or
... where, in mix of zero-length and nonzero-length arguments, zero-length wins and the nonzero-length arguments are truncated to zero-length