@Corné-Haast
open find/replace dialog and check regular expressions. (bottom left)
For find use:
sdval=".+?"
and for replace your value.
The regex looks for sdval=" literally followed by any char until the next double quote appears.
. = any char
+ = at least one char expected
? = non-greedy
More infos how npps regex engine works can be found here.
Cheers
Claudia