@WORDS[["sep_list",]string]: Returns the number of words in string.
The default list of separators for @FIELD, @FIELDS, @WORD and @WORDS consists of space, tab, and comma. You can use the optional first parameter, sep_list, to specify the separators that you wish to use. If you want to use a quote mark as a separator, prefix it with an Escape character. Alphabetic characters in sep_list are case sensitive.
@FIELD and @FIELDS differ from @WORD and @WORDS in how multiple consecutive separators are counted. @WORD and @WORDS consider a sequence as a single separator, and ignore separators at either end of string. In contrast, @FIELD and @FIELDS count each occurrence of a separator individually, including those at either end of string.
If string is double quoted, you must specify sep_list.
echo %@words[How many words in this list?]