I just noticed two anomalies re the way Therion records survey length. Data recorded like this... data cartesian from to northing easting altitude 7 7a 90 -99 4.5 7a 9 97 -9 4.5 9 10 31 -22 0 are reported as zero length surveys in the Therion survey-list output. A bug? Depends on point of view I guess, cartesian implies no actual distance measured, so zero survey length, but the definition of two points does have some parallels with a 'shot' and hence survey length. I contrast, 'no survey' leg lengths are recorded as accumulating survey length. ie flags surface fix 1 -41.1724 172.4155 572.6 fix 2 -41.20492 172.2789 574.04 fix 3 -41.21414 172.1513 574.04 etc data nosurvey from to 1 2 2 3 3 4 These are reported by Therion as accumulating survey length. I can see that the desirable behaviour of each of these scenarios might be different depending on one's particular intention. In the case of the particular data where I found this issue, I would prefer the; - underground cartesian data to accumulate length - surface nosurvey data to accumulate length, as it in fact does (I am joining up points from a gps trail) but in general I would expect; -underground nosurvey data to record zero length, because it will generally be a sound or sight connection with no actual survey, hence not surveyed length. I have not checked any of the other data survey formats. Other peoples thoughts on this? Bruce