Reserved

The reserved words in R's parser are if else repeat while function for in next break TRUE FALSE NULL Inf NaN NA NA_integer_ NA_real_ NA_complex_ NA_character_ … and ..1, ..2 etc, which are used to refer to arguments passed down from a calling function, see ....

Details

Reserved words outside quotes are always parsed to be references to the objects linked to in the ‘Description’, and hence they are not allowed as syntactic names (see make.names). They are allowed as non-syntactic names, e.g.inside backtick quotes.