Delimiting arguments

When parsing a line for an argument, initial and trailing blanks are ignored. In addition, an argument field is delimited by a comma, or some of the special characters (particularly the comment, end of input, special delimiter characters). If an argument has no non-blank characters before a delimiter is reached, the argument is said to be an empty, null, or skipped argument. Conventionally, an empty argument is to be treated as indicating some default value. For example:

    foo          		| is a line consisting of a single argument `foo'.

    foo bar

    foo,bar

    foo   bar

    foo,  bar

    foo  , bar 		        | are all lines with two arguments `foo' followed

    foo|bar     		| by `bar'.

    ,, foo       		| have two initial empty arguments followed by

     , , foo     		| `foo'.

    bar,,foo     		| has `bar', an empty argument and `foo'.