Sequentially numbering but only for certain rows in an attribute table

[AlexZacher]

Hello!

I want to sequentially number only particular features (headstones) in a table with location data for different types of stones, and I'm having trouble figuring out how to code this in Python.

I keep getting errors when I use SequentialNumber() and try to call the headstone field in the code block. Typing !Headstone! instead gives a syntax error.

Basically, I want to be able to number (and later label) only the headstones. Their order in the table is important too.

 Is there a better way to do this? Any help would be greatly appreciated!

[AlexZacher]

Thanks! That's what I ended up doing. I'm accepting this post as the solution because it most thoroughly explains how to make this method work.