A place for line-item notes on the invoice?

["James D. Ivey" <..hidden..>]

Broader question first: is there a comprehensive list of variables that
can be used in templates? That would be very helpful.

More specific question: how can I include line-item notes on the
invoice data-entry form in the invoice generated through the template?

I'm referring to the notes that appear just below the description and
between the delivery date and the serial number on the data-entry form
for generating an invoice. I tried "<?lmsb notes ?>" in the item table
of invoice.tex without luck.

Thanks in advance for any help....

Regards.