REG_ECOLLATE
(void)REQUIRE(c != '-' && c != ']', REG_ECOLLATE);
(void)REQUIRE(EATTWO('=', ']'), REG_ECOLLATE);
(void)REQUIRE(EATTWO('.', ']'), REG_ECOLLATE);
SETERROR(REG_ECOLLATE); /* neither */
{REG_ECOLLATE, "REG_ECOLLATE", "invalid collating element"},