John I create data based on where I'm going to hunt/shoot. I don't need to have this data created and in hand as I don't expect to be called up to hunt with only a few hours notice. I do check ahead of time as to elevation and temp and bring/take charts along and check them on-site once I arrive. Wind deflection changes with altitude so I include windage figures too. I've hunted to 13,000 ft Above Sea Level (ASL) In the past I've found that for distances out to 400 yards there is little trajectory difference for a high BC projectile. I have found that my 100 yard zero "moves" as I travel around the country and I re-zero at the new site as a result of this observation. Len posted similar observations and I don't know if it was ever fully answered or solved. I have small data charts that I laminate and carry in the Eagle Stock Pack. I carry a basic three (3) "all conditions" set and make a specific set once I know where I'll be. Good set of questions. Make one a little more mindful when folks as for trajectory data? What's their "home" environment, altitude etc, most published stuff is Standard Temp and Pressure (STP) I believe.