Hello I was just wondering if this is correct, but it would appear that when searching the database output all surveys contain at least 2 centreline ids Attached is the Forbidden.th file which has only one centreline/endcentreline pair, but the result below seems to show that there are 2 centreline id per survey when there is a centreline/endcentreline, of which one always have zero length. There is one id in files where there are no centreline/endcentreline, Eg CheddarCatchment which is the file that puts it all together, again this has zero length. This could be the way that it is designed, but it does seem to lead to lots of redundant data. Here is the search (I added the names in for ease of reference) SELECT C.`TITLE`, C.`ID`, C.SURVEY_ID, SURVEY.NAME, C.`SURFACE_LENGTH`, C.`LENGTH` FROM CENTRELINE C, SURVEY where SURVEY.ID=C.SURVEY_ID Limit 30 which gives this result (also attached as csv, as email can make a mess of tables) TITLE ID SURVEY_ID NAME SURFACE_LENGTH LENGTH 2 1 0 0 12 11 CheddarCatchment 0 0 14 13 Blackmoor 0 0 15 13 Blackmoor 0 105.3 18 17 BoneHole 0 0 20 19 BH_Surface 0 0 21 19 BH_Surface 13.49 0 22 19 BH_Surface 110.86 0 25 24 BH_Entrance 0 0 26 24 BH_Entrance 0 26.77 29 28 BH_FirstPitch 0 0 30 28 BH_FirstPitch 0 23.23 33 32 BH_PerforationChoke 0 0 34 32 BH_PerforationChoke 0 41.57 37 36 Bone2 0 0 38 36 Bone2 0 65.52 42 41 Box 0 0 43 41 Box 0 55.96 46 45 charter 0 0 48 47 OldCave 0 0 50 49 Chiaroscuro 0 0 180 49 Chiaroscuro 0 89.01 183 182 Entrance 0 0 616 182 Entrance 0 103.07 617 182 Entrance 0 281.2 620 619 Forbidden 0 0 720 619 Forbidden 0 36.84 723 722 Midsummer 0 0 812 722 Midsummer 0 31.38 815 814 ReadsInlet 0 0