The writer of any document can abbreviate however they please. While most people do tend to follow standard abbreviations, it’s possible for someone to occasionally use an atypical abbreviation.
While reviewing a court case from the early 19th century in Virginia, I was almost convinced I had discovered a new relative: Eli Tinsley. The “Eli” abbreviations were used in a summary list of court depositions and it was clear that “Eli” was a reference to Elizabeth and not a separate person named Eli. The clerk also used “E” as an abbreviation for Elizabeth in the same summary list.