- Blank characters count as a value, so even a single blank stored as a value will cause the field to be stored with the symbol.
- Even if you delete a value from a symbol, the field name may still appear in the list when you use the Part Attributes command as the symbol editor keeps its own temporary symbol table for the duration of a program session.
- To tell if a non-standard field is stored with a symbol, just create a new, empty design and place the symbol in it. If there are any non-standard fields defined in it, you will get a warning box indicating that new field definitions are being added.
Background: How Attribute Fields are Stored with Symbols
When a symbol is stored in a library, it is a separate entity with its own list of symbols and the associated values. Each item is stored as a field name/value pair with no reference to any outside table. Attribute fields with no value are not stored with the symbol. I.e. to delete a field from the symbol that you are currently editing, you just remove the value.
However, the symbol editor has a feature that may cause a field to appear to be lingering with a symbol when it really isn’t there. If you’re making a number of parts in a row, it is annoying to have to keep redefining the same field, so for this reason, the symbol editor keeps its own symbol table that lasts for the duration of the program session. If you create one part and define a new field “MyPart”, then come back a few minutes later and create a new part, “MyPart” will appear in the list because the editor has added it to its table. This does not mean that it has been added to the symbol, it is just in the editor’s table There is no way of removing items from this temporary table, short of quitting the program and restarting, but items in this table have no permanent affect on the symbols that are edited during that time unless a value is explicitly placed in that field.