in the 'Parts' panel.
Start the 'Library editor' and after selecting a library hit the
control button in the 'Parts' panel.
The following dialog is displayed:
Set the attributes as described in "Library part attributes".
Multi-part symbols are created by setting the 'Multi part' checkbutton (at the top of the dialog) in the section labeled 'Multi part setup'. Entering the number of parts in the entry box. For a single part item leave the checkbutton 'unset'.
After pressing OK the schematic library editor will be displayed
(see Library part
schematic) (having one panel for each part of the symbol). In
this case there are three parts. Each panel can be edited to
display the required symbol part.
The rest of the process is the same as described for creating attributes and schematics.
When the symbol is selected for pasting into the schematic each part
of the symbol is pasted in turn with the Id remaining the same and the
part identifier updating. i.e. U1-1 U1-2 U1-3 would be placed in
this case. If pasting continues with the same symbol then U2-1,
U2-2 etc will be pasted.