1-The built-in Houdini materialX Catalog is saved as a .db file (materialCatalog.db), i.e. why not not just a directory structure? This way one does not need to a program/api to access it, they will be just just flat files that can be inspected and copied easily(see use case below)
2-How to duplicate a material defined in the Catlog, then edit it, and finally save it as a new material? Curently, I drag the material to the left panel (ie. Material Tree), then use "Edit Material Network" to load the material? then Right click to save the new material, which will not appear in the catalog because it's a DB? Maybe I am doing something wrong...