Rdo_comment(x = "%%")
Rdo_tag(x, name)
Rdo_verb(x)
Rdo_Rcode(x)
Rdo_text(x)
Rdo_newline()x with its "name (Rdo_tag),
"TEXT" (Rdo_text),
"VERB" (Rdo_verb) or
"RCODE" (Rdo_Rcode).x, effectively
assuming that the caller has prepared it as needed.
Rdo_tag sets the "x to name.
The other functions are shorthands with a fixed name and no second
argument.
Rdo_comment tags an Rd element as comment.
Rdo_newline gives an Rd element representing an empty line.