initiative modifiers

I'm trying to use an equipment mod to adjust initiative on a 5e character sheet.  Under the equipment I've tried "initiative_bonus:+2", I've tried "initiative: +2", I've tried "initiative_mod: +2" and just about everything else I can think of in both the "prop" field and the "mod" field.  Other than typing it as a permanent modification in the attributes list, I haven't been able to get it to show up on the character sheet. Suggestions?

I don't think that is one of the equipment-modifiable fields. If you can think of a standard magic item that does this, you can try dragging that onto the character sheet and see what syntax it yields, but I don't think this is the case.

Thanks Keithcurtis, I appreciate it.  I had found a couple of lists that implied this but I was hoping they were just incomplete.  I guess we'll do it the hard way.  

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