File types used by Carlson Civil include:
.crd – Point data, coordinate file
.rw5 – raw survey data, contains all observations
.cl – centerline, describes a 2D alignment
.tin – Surface, newer format, more efficient than .flt in most cases, especially for machine control
.flt – Surface, original format
.grd – Surface grid file, used for volumes
.cfg – Stores configuration settings
.fld – Field to Finish file, stores rules for inserting symbols for points (LDT Description Key functionality) and automated linework functionality (Autodesk Survey Figures equivalent)
.lot – Lot file, stores parcel geometry
.adf – Annotation Default file
.pro – Profile file
.mxs – Section Alignment file
.grp – Point Group definitions
.rdn – Roadway Networks
.sct – Road Sections
.tpl – Road Templates
.rdf – Road Design Files