as in:

#4 DWLS x 2' 6" @ 48" oc

#4 is 1/2 inch rebar
oc is on center
what is DWLS?

DWLS is not listed on the abbreviation details.

It may be Duel Wavelength Laser Sourse

I'll bet it means Dowels since DWL is Dowel. Abbreviations which can be used on drawings (http://academics.triton.edu/faculty/fheitzman/abbrev.html)

The reference has many abbreviations that might be useful for you.