Base rnd, each side: Multiple of 4 + 3 + corner sts.
Begin 4 sts to left of corner st.
Rnd 1: Ch 1, sc in same st, ch 7, skip 3 sts, *[sc in next st, ch 7, skip 3 sts] to corner st, 3 sc in corner st, ch 7, skip 3 sts; rep from * around, join with slip st to first sc.
Rnd 2: Ch 1, sc in same st, *[ch 3, skip 3 ch, sc in center ch of ch-7, ch 3**, sc in next sc] to corner st, ch 5 for corner space, skip 1 sc, sc in next sc; rep from * around, ending last rep at **, join with slip st to first sc.
Rnd 3: Ch 1, sc in same st, *[ch 7, skip 1 sc**, sc in next sc] to corner space, (ch 3, sc, ch 3) in corner space, sc in next sc; rep from * around, ending last rep at **, join with slip st to first sc.
Rnd 4: Ch 1, sc in same st, *[ch 3, sc in center ch of next ch-7, ch 3**, sc in next sc] to corner, ch 3, sc in corner sc, ch 3, sc in next sc; repeat from * around, ending last rep at **, join with slip st to first sc.
Rnd 5: Ch 1, sc in same st, *ch 7, skip 1 sc, sc in next sc; rep from * around, omitting last sc, join with slip st to first sc.
Rnd 6: Ch 1, sc in same st, *ch 3, (sc, ch 3, sc) in center ch of ch-7, ch 3, sc in next sc; rep from * around, omitting last sc, join with slip st to first sc. Fasten off.