This function is introduced solely for the purposes of translating it via SKSI into the SQL function 'StartPoint' which is defined in the the Open GIS Simple Features Specification for SQL. (OGC Start Point Fn LINESEGMENT) returns the 'start' point of LINESEGMENT. Ontologically speaking, LineSegments don't have an orientation, so designating one endpoint as its 'start' point is arbitrary. However, in OGC compliant databases, stored LineSegments do have start and end points, even if they are arbitrarily assigned as such. See also the corresponding CSQL function, CSQL Start Point Fn.