From the NIH National Library of Medicine (NLM). Currently XML processing tools only.
MeSH XML utility functions.
MeSH XML Download: https://www.nlm.nih.gov/mesh/download_mesh.html Doc: https://www.nlm.nih.gov/mesh/xml_data_elements.html
<DescriptorRecord DescriptorClass="1"> 1 = Topical Descriptor. 2 = Publication Types, for example, 'Review'. 3 = Check Tag, e.g., 'Male' (no tree number) 4 = Geographic Descriptor (Z category of tree number).
Category "C" : Diseases Category "F" : Psychiatry and Psychology Category "F03" : Mental Disorders Thus, include "C*" and "F03*" only. Terms can have multiple TreeNumbers; diseases can be in non-disease cateories, in addition to a disease category.