With Arnold there are two things in an ASS file that specify the location of a texture file:

For example, if the texture filename was a relative path, you might have something like this in an ASS file:

options
{
 ...
 texture_searchpath "//server/projects/test"
 ...
}

MayaFile
{
 ...
 filename "sourceimages/noicon.png"
 ...
}