Hi Spike - In AVO usage, the X indicates the vertical broadband signal has been filtered. (otherwise, they're much noisier) Thanks, cheryl -------- Spike Page wrote: I have noticed that a few of your webicorder channels have names that end in "X" instead of the usual (as listed in SEED) orientation designations such as Z, N and E or 1,2 and 3 etc. MGOD BHX AV is one example though there are a handful of others. Does that represent a nontraditional orientation or is it a less common variant of one of the orthogonal designations? Thanks in advance for your reply. Spike "Volcanohead" Page -- Cheryl Cameron Geologist, Alaska Volcano Observatory Alaska Division of Geological & Geophysical Surveys voice: 907-451-5012 fax: 907-451-5050