The normal attribute used for a parent component tag is TAG1 with the child being TAG2. However you are able to split the component tag on either the parent and/or the child symbol by using TAG1_PART1, TAG1_PART2, TAG1_PARTX (as well as TAG2_PART1, TAG2_PART2, TAG2_PARTX attributes.
These alternatives to TAG1 and TAG2 allow you to split a tag name into two pieces which may for example allow you to position one piece of the tag above the other on the symbol. Drawings can contain a mix of both types of component tagging i.e. split tags and single TAG1 or TAG2 attributes.
If a parent symbol has the single TAG1 attribute, related child symbols can have split tag attributes and vice versa. If a parent symbol has split tag attributes, related child symbols can have the single TAG2 attribute. The default value character string of the symbol for the tag should be annotated as a default value on the TAG1_PART1 attribute definition.