On the Schematic Design toolbar, click Connect > Module.
In the Select dialog, provide a descriptive module name in the New field, and a short Prefix used to label the module. The module is attached to the cursor.
Click to place the module. It is labeled <Prefix>-1, and generates a new schematic sheet titled <Name>: 1. If you place another module, the label and sheet titles are the same, but incremented to 2.
To resize a module, Ctrl-Click to select it, then change the size in Inspector.
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