device= is the device name of the symbol
device= should be placed somewhere in the symbol and made invisible. This is a free standing or floating attribute. If the object is a graphic then device= should be set to none (device=none) and attach a graphical= attribute (graphical attribute). Do not confuse this attribute with just having a text label which the device name. Do not put spaces into the device name; there are some programs which dislike spaces in the device specifier. Generally the device name is in all caps.
Examples:
device=7400 device=CONNECTOR_10 device=NPN_TRANSISTOR