The commercial at is most often seen on invoices and billings and has received great exposure as the separator seen in e-mail addresses, i.e., dogtrotxp@attbi.com. Yet this character is very old and seems to have been developed from the clerks’ handwritten word, at. The commercial at probably developed as sort of a shorthand version of the a and the letter t and like the two letters et which became our ampersand, the commercial at became a special character -- similar to a ligature (two or three letters combined into one type face), but unlike the ligature, the original letters of the commercial at are not readily apparent.

       The ditto is most often seen today as this mark, " , but in our older documents we often see the ditto abbreviated as do, d^o, or d^o. It is the same type of abbreviation style as first and last letters used for the name William, W^m. Beginning genealogists sometimes stumble over the do when they view their census images.



An 1829 usage of do, in this case indicating the ditto is a repeat of the word Installments.