Subprograms not in modules
While browsing the source code I've come across a number of subroutines (and a few functions) that are not part of modules and that seem to be called without any explicit interfaces. Reasonable
grep searches on the files in the top
Src directory of the current rel-Max-1 branch (ba791d41) suggest that there are 134 Siesta Fortran files that contain 190 subprograms that are not contained in modules.
Modern Fortran best programming practices require that explicit interfaces are available for subprograms, so that argument checking can take place. The easiest way to achieve this is to place subprograms inside of modules.