If you use a Uuid field you can set the type to K-UUID. This works fine for setting up an argument to filter a grid using the "Define Arguments" button on the grid builder.

However, if you use x-basic to filter a set like this:
tbl = table.open("[Pathalias.ADB_path]\web_total.set")
query.filter = "Uuid = \"" + uuid + "\" "
query.order = ""
indx = tbl.query_create()
it will not work if the field type for Uuid is set to K-UUID type, even if you use
"Uuid = \"" + remspecial(uuid) + "\" "
in the filter expression.

When you change the type of the Uuid field to character, with a lenght of 36, then the expression will work. Thus, if you are going to filter as above on the Uuid, it is best to define Uuid as a character value.