cvecs ← {prim supp} ##.words cvec           ⍝ Source vector split into words.

The character vector argument is split into words.  A word is defined as a sequ-
ence starting with a character from [prim],  the primary alphabet and continuing
with characters from both this and the supplementary alphabet [supp]. If no left
argument is supplied,  prim defaults to A-Z, a-z, Á-õ and supp to 0-9.  A simple
left argument is interpreted as the primary alphabet, with a null supplementary.

Examples:

words 'It''s only words,'               ⍝ Word split at A-Z,a-z,Á-õ.
┌──┬─┬─┬─┬────┬─┬─────┬─┐
│It│'│s│ │only│ │words│,│
└──┴─┴─┴─┴────┴─┴─────┴─┘

words'4x1+x2'                           ⍝ Trailing 0-9 bind to left.
┌─┬──┬─┬──┐
│4│x1│+│x2│
└─┴──┴─┴──┘

(lcase ⎕a) words'mete and dole'         ⍝ Simple alphabet split.
┌────┬─┬───┬─┬────┐
│mete│ │and│ │dole│
└────┴─┴───┴─┴────┘

(lcase ⎕a) words':If ⎕IO=0'             ⍝ Split at a-z.
┌──┬─┬──────┐
│:I│f│ ⎕IO=0│
└──┴─┴──────┘

(⎕A,lcase ⎕a) words':If ⎕IO=0'          ⍝ Split at A-Z,a-z.
┌─┬──┬──┬──┬──┐
│:│If│ ⎕│IO│=0│
└─┴──┴──┴──┴──┘

(':⎕',⎕A,lcase ⎕a) words':If ⎕IO=0'     ⍝ Split at :,⎕,A-Z,a-z.
┌───┬─┬───┬──┐
│:If│ │⎕IO│=0│
└───┴─┴───┴──┘

(⎕D,':⎕',⎕A,lcase ⎕a) words':If ⎕IO=0'  ⍝ Split at 0-9,:,⎕,A-Z,a-z.
┌───┬─┬───┬─┬─┐
│:If│ │⎕IO│=│0│
└───┴─┴───┴─┴─┘

⎕A (lcase ⎕a) words 'ThatsAllFolks!'    ⍝ Split at A-Z; a-z trail.
┌─────┬───┬─────┬─┐
│Thats│All│Folks│!│
└─────┴───┴─────┴─┘

(⍳10) words 1 0 0 2 3 0 4 5 6           ⍝ Numeric "alphabet".
┌─┬───┬───┬─┬─────┐
│1│0 0│2 3│0│4 5 6│
└─┴───┴───┴─┴─────┘

(⍳10) 0 words 1 0 0 2 3 0 4 5 6         ⍝ Numeric;  0s trail.
┌─────┬─────┬─────┐
│1 0 0│2 3 0│4 5 6│
└─────┴─────┴─────┘