Where is the Deluge "Sendmail" template attachment as PDF function documented?

Where is the Deluge "Sendmail" template attachment as PDF function documented?

HI, I can't see this function documented anywhere, despite a few examples of its use showing up in replies to various posts. I've tried using this function in my sendmail command (like for example)

sendmail

from : zoho.adminuserid
to : zoho.adminuser
subject: "test" 
message : "test      " 
attachments:template:Generated_Supplier_Invoice as PDF
]

but all i get when I try to save is:

"in user defined function form link name and record id are mandatory for template attachment"

and when I try adding an ID parameter like this:

sendmail

from : zoho.adminuserid
to : zoho.adminuser
subject: "test" 
message : "test      " 
attachments:template:Generated_Supplier_Invoice ID as PDF
]

I get the dreaded "Improper statement" error.

What is the correct syntax for this function please?

Steve