B757 Captain reported receiving a GPWS terrain alert on final approach to Runway 10L at SFO even though the aircraft was on proper track and vertical path.

Narrative

We were cleared for the RNAV (GPS) 10L for SFO outside of NORMM. After passing NORMM at approximately 3500 ft. we set TDZE; were in VNAV Path with speed intervention was set to the assigned '180 kts. ' to XATTU'. FO (First Officer) was Pilot Monitoring and had his FMC on prog page 2 to monitor track error. Approaching XATTU; I confirmed FMA of VNAV PTH and that touchdown was set in the altitude window. At XATTU; I began slowing to target speed and configuring to landing flaps. At approximately 1500 ft. and 1000 ft. Radar Altimeter (RA); I called for the missed approach altitude to be set and we got a 'terrain; terrain' GPWS alert. We were still on course and path and I could see the REIL. I positioned my thumb on the TOGA button on the thrust lever in preparation for the 'escape maneuver.' I paused momentarily before executing the escape maneuver to confirm in my mind whether the 'caution' level 'terrain; terrain' required a mandatory use of the maneuver. During this pause there were no other alerts and I could now see the runway clearly as well as the city lights below and our RA which was above 1000 ft. At this point I believed executing the escape maneuver was not necessary and continued the approach. At approx. 800 ft. I disconnected the auto-pilot and made a normal landing. After arrival at the gate; the FO and I discussed the various GPWS vs EGPWS alerts and consulted the flight manual. There is some contradiction in the flight manual. The systems chapter lists 'Terrain' as a caution level message; but the supplementary chapter has it as a warning requiring the escape maneuver at night there is an exception for day visual. However; the EGPWS 'Caution; Terrain' does not require the escape maneuver but an adjustment to the flight path. When the 'terrain; terrain' aural sounded; I initially thought of the EGPWS caution which caused me to pause. In hindsight; I should have executed the escape maneuver upon hearing the 'terrain; terrain.'