I got it working with this addition: "\"

$Drive = readprofilestring("@curdir\"+"test.ini","test","drive")
$unc = readprofilestring("@curdir\"+"test.ini","test","UNC")

and " " after $tab, otherwise it looks for $tabthere. $b$cr$tab@Serror is OK because $ and @ signify the end of a var by specifying the start of another var or macro.

$nul = execute('? "$tab There was Error#@error mapping $drive to $b$cr$tab@Serror"')

cj