A B-747 flight crew cleared to taxi from the ORD South Cargo Ramp to hold short of Runway 28 via Tango; November and Sierra during IMC was chastised for not holding short of Sierra. Flights landing on 28 reported interference with the GS signal. The flight crew was unable to find any documentation specifying the area as a non transgression zone and there was no ILS hold short line located on November short of Sierra.

Narrative

The ORD Ground Controller instructed us to taxi T-N-S to Runway 28. After initial check-in with the Tower he cleared us to hold short of Runway 28 at S. As we were in the turn from Taxiway N onto S; the Tower emphatically instructed us to hold our position; and told us that we were not supposed to be in the area we were in. I stopped the aircraft in a partial turn from N on to S. The Tower then advised three landing flights there was an aircraft (us) in the glide path reception zone. The first landing aircraft reported interference to the glide slope while on approach. All three aircraft continued to a landing. My crew all agreed they heard the same instructions; and we were in compliance with ATC's clearances. We re-reviewed the ORD airport page and NOTAMS; but found no depictions or information that indicated a need to stop short of Taxiway S. In addition; the airport diagram is not to scale and leads a viewer to believe there is more taxiway area after making the turn on to S. In reality it is a short; tight turn. I initially intended to stop the aircraft on N; but interpreted the Tower instructions to mean to turn onto S and hold short at the designated (and observed) hold short point. This would be consistent with the routine and normal practice of ATC to release an aircraft for takeoff between the sequence of landing aircraft. We were subsequently cleared for takeoff. Remainder of flight was uneventful.If taxi on S short of Runway 28 is unacceptable in low visibility situations the airport page needs verbiage and/or depiction to have aircraft stop clear of this critical area. Lacking that; ORD ATC must clarify taxi instructions [to hold short of S on N].