WSSQL does not accept "key" as column name

Entering
SELECT seq, fill FROM hthor::nhtest::testfile_cmp
works correctly, but
SELECT key, seq, fill FROM hthor::nhtest::testfile_cmp

results in ANTLR parse error

Error while parsing: ANTLR Error 3 :
Near [Index: 2 (Start: -1207886377-Stop: -1207886375) ='key', type<65> Line: 1 LinePos:6]
: cannot match to any predicted input...