There is no meta-statement within the file, although meta-information is effectively embedded in the file name, but this functionality in confined to stud primitives. Each primitive (files in ldraw/p) that matches stud*.dat will have an equivalent stu2*.dat partner in the same folder.
This dates back to the original LDraw implementation and is probably not how we would do it now. In concept it is not that different to the hi-res primitives which are stored in ldraw/p/48 and (when present) can be substituted for normal-res files of the same name. I wouldn't have an issue moving the ldraw/p/stu2* files to ldraw/p/8/stud* except that MLCad has a hard coded expectation and whinges if a stu2* file is not found.
This dates back to the original LDraw implementation and is probably not how we would do it now. In concept it is not that different to the hi-res primitives which are stored in ldraw/p/48 and (when present) can be substituted for normal-res files of the same name. I wouldn't have an issue moving the ldraw/p/stu2* files to ldraw/p/8/stud* except that MLCad has a hard coded expectation and whinges if a stu2* file is not found.
Chris (LDraw Parts Library Admin)