A B737-300 QRH Leading Edge (LE) Device Transit Light checklist wording did not include the condition of the devices being fully retracted in the initial condition explanation so the crew was uncertain about what the correct landing flap configuration and speed was.

Narrative

While configuring to land; we got a LE Flap Transit light. We immediately looked at the overhead panel and out the windows and confirmed that there was no leading edge devices extended at all. This was not that big of a surprise because of our previous maintenance issue with this aircraft earlier on this leg. We executed a normal go-around and declared an emergency with Approach Control. We began to reference the QRH page H-19 FLAPS; LEADING EDGE: LE Flaps Transit checklist. The textual information of page H-18 (During Configuration For Landing) states; 'Leading edge devices have extended asymmetrically or have failed to move to the full extend position as appropriate.' We knew this was not the case; but the checklist did not provide any other path of action and no other checklist seemed to be more appropriate. We continued with the checklist; but were very uncomfortable with an approach speed of VREF 15+5 set as REF and a target speed of five knots above that for the reported winds. The checklist did not ever mention the possibility of executing this approach without any leading edge devices extended and we felt that this situation may significantly increase our stall speed. We knew from previous troubleshooting with Maintenance that we could extend the leading edge devices and TE flaps with the ALT Flaps switch; but were not directed to do so by the checklist and did feel comfortable going down that road without QRH guidance. I told the Captain that I planned on adding about 20 knots to the approach speed as a safety margin and that I would bleed it off on a short final. He concurred with this decision. We coordinated for the longer runway; 12R. We configured the aircraft per the checklist on about a 15-mile final and flew an otherwise uneventful ILS approach to landing. The lack of any information in the QRH specifically mentioning an approach with no leading edge devices at all; gave us very little confidence that we were using the correct checklist for our situation. Examination of whether this is indeed the proper procedure for this situation is warranted. If it is indeed the proper procedure; then guidance needs to be added to acknowledge this. If it is not; then guidance needs to be provided for this situation.