CREATE TABLE "table1_1574968_1" (
  "language" text,
  "creator" text,
  "first_public_release_date" text,
  "editor" text,
  "viewer" text
);

Question: Which viewers have the language of troff (typesetter runoff) , groff (gnu runoff)?
SQL: SELECT "viewer" FROM "table1_1574968_1" WHERE "language"='troff (typesetter runoff) , groff (GNU runoff)';

Question: Who is the creator when the view happens to gddm, afp viewer?
SQL: SELECT "creator" FROM "table1_1574968_1" WHERE "viewer"='GDDM, AFP viewer';