parse_Rdtext(text, section = NA)section is given, then parse_Rdtext parses
text as appropriate for the content of section section.
This is achieved by inserting text as an argument to the TeX
macro section. For example, if section is
"text and a closing "section is NA then parse_Rdtext parses it without
preprocessing. In this case text itself will normally be
a complete section fragment.parse_Rd. This is done for at least two reasons. Firstly,
parse_Rd works most reliably (at the time of writing this)
from a file. Secondly, the saved file may be slightly different
(escaped backslashes being the primary example).
It would be a nightmare to ensure that all concerned functions know
if some Rd text is read from a file or not.
The (currently internal) function .parse_Rdlines takes a
character vector, writes it to a file (using cat) and calls
parse_Rd to parse it.parse_Rdpiece