Page 103. ↑ GPS-IS-200, § 20.3.3.5.1 (p. 108–109). ↑ GPS-IS-200, § 40.3.3.5.1 (p. 207–208). ↑ US Coast Guard GPS FAQ ↑ GPS-IS-200, § 30.3.3 (p. 140). ↑ Numbered starting from 1. Bit 1 is the first bit in the message and bit 300 is the last one. ↑ TOW count for the beginning of the next message. It uses the same format than the truncated TOW in LNAV. ↑ GPS-IS-200, § 30.3.4.1 (p. 190). ↑ GPS-IS-200, § 3.3.3.1.1 (p. 39) Note that synchronization is described in the IS in terms of X1 epochs, which occur each 1.5 seconds and are synchronized with start/end of GPS week. ↑ GPS-IS-200, § 3.3.3.1.1 (p. 39). ↑ "Interface Specification IS-GPS-200 Revision D" (PDF).