I am guessing you are referencing post #38 (??) "...ASA 100 (summer speed) ortho ("X2Ag")..." I can see how that was confusing. I meant that the emulsion is ASA 100 in the summer, assuming full sun, mid-day, and a high energy developer. That's the thing with pre-modern emulsions. It is meaningless to assign a speed to them without specifying the shooting conditions. Every photography book published in the late 1880's and early 1900's had a chart of latitudes and times of year with numbers like filter factors to estimate exposure compensation (i.e. "speed"). Since the emulsions see very little beyond UV, the higher the UV, the "faster" the emulsion. "x2Ag" is around ASA 25 at Christmas time.