There are two types of metal libraries available in Sonnet: global and local. The metal libraries contain standard definitions for metal types, both planar and via, which may be used in your projects. There isn't a difference between the global library and local library. The names refer to how they are used. The global library would usually be used as a group wide library of standard metals for a group of designers.
There is a default global library supplied by Sonnet which contains definitions for some common metals, both planar and via. The default location for the global library is in <Sonnet Data Directory>/data/libraries where <Sonnet Data Directory> is the directory in which your Sonnet software data is installed. You may choose to use this location or can save this library in another location.
The local library would usually be used as the user's own library of metal definitions. This library may be stored in a location of the user's choice. You use either the Planar Metal Editor dialog box or the Via Metal Editor dialog box to add, edit and delete entries to these libraries.
For instructions on adding planar and via metals to a metal library, editing metals in a metal library or using metals defined in a metal library, please refer to Metal/Bricks.