I wonder how one can add characters such as (yes, space!), ' (single quote), " (double quote), etc., to iskeyword.
This is not a theoretical exercise. The purpose is iabbrev for these. I noticed that if you add a character to iskeyword, then use it for iabbrev, and then remove it from iskeyword, the abbreviation still works.
Adding space, would make it possible to e.g., to define two word abbreviations.
EDIT I double checked. This works. Take the following as an example:
set iskeyword+=^
set iskeyword
iabbrev ^0 ⁰
set iskeyword-=^
set iskeyword
iabbrev 'a fooandiabbrev "a foowork without having to mess withiskeyword. – muru Jan 08 '16 at 10:38