variable substitution of Tolerance

[Ken Lord]

Hi list,

I've been trying to modify the TOLERANCE value of a layer in my
mapfile, using variable substitution, Windows CGI mapserver:

LAYER
...
  TOLERANCE %myvariable%
...
END

But it crashes when it hits the first '%', stating its an unknown symbol. 

Is this parameter untouchable with variable substitution? 

I haven't had this problem using variable substitution elsewhere in my
mapfile, such as modifying connection strings.

Thanks,
Ken Lord
Vancouver BC