Shad is published at last Vassal

[Shad]

Does VASSAL allow for double-blind play, i.e. handling search functions etc? That was one of the best features of the spreadsheet / VB program Russel and I made to handle GWAS operational. Double-blind makes for awesome GWAS / SWWAS games.

Not out of the box. It supports custom Java scripts, so if you could make it work within Excel someone who knows Java could certainly write a plugin for the VASSAL client.

However, such enhanced functionality is very rarely seen in VASSAL mods. So for most practical purposes I'd say no, it doesn't support double-blind play without a referee.