Manu propria is a Latin

Latin

Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...

 phrase in the ablative case

Ablative case

In linguistics, ablative case is a name given to cases in various languages whose common characteristic is that they mark motion away from something, though the details in each language may differ...

 meaning "(signed) with one's own hand". In its abbreviated

Abbreviation

An abbreviation is a shortened form of a word or phrase. Usually, but not always, it consists of a letter or group of letters taken from the word or phrase...

 form (m.p.), it is sometimes used at the end of typewritten or printed documents or official notices right after the name of the person(s) who "signed" the document exactly in those cases when there is no handwritten signature

Signature

A signature is a handwritten depiction of someone's name, nickname, or even a simple "X" that a person writes on documents as a proof of identity and intent. The writer of a signature is a signatory. Similar to a handwritten signature, a signature work describes the work as readily identifying...

 there.

It is also found in several ancient documents in front of or after the writers signation at the end of the document.

Ordinary personal checks

Cheque

A cheque is a document/instrument See the negotiable cow—itself a fictional story—for discussions of cheques written on unusual surfaces. that orders a payment of money from a bank account...

 frequently include the abbreviation at the end of the signature line.

Richly decorated manu propria was frequently used by medieval dignitaries and literates to verify authenticity

Authentication

Authentication is the act of confirming the truth of an attribute of a datum or entity...

 of hand written documents.

Later, official documents were routinely accompanied with this abbreviation, for example declaration of war on Serbia

To my people

To my peoples!, in German An meine Völker!, in Hungarian Népeimhez!, in Czech Mým národům! was a manifest signed by Franz Joseph I, Emperor of Austria-Hungary in Bad Ischl on July 28, 1914...

 by Emperor Franz Joseph

Franz Joseph I of Austria

Franz Joseph I or Francis Joseph I was Emperor of Austria, King of Bohemia, King of Croatia, Apostolic King of Hungary, King of Galicia and Lodomeria and Grand Duke of Cracow from 1848 until his death in 1916.In the December of 1848, Emperor Ferdinand I of Austria abdicated the throne as part of...

 from 1914 ends with m.p..

Usage in the 18th century

mppria was commonly used in the 18th century. However, it was not only used for Latin documents.

• Full autograph title-page of Symphony no.97 by Joseph Haydn
  Joseph Haydn
  Franz Joseph Haydn , known as Joseph Haydn , was an Austrian composer, one of the most prolific and prominent composers of the Classical period. He is often called the "Father of the Symphony" and "Father of the String Quartet" because of his important contributions to these forms...
  
   which reads 'Sinfonia in C/di me giuseppe Haydn mppria. '
• Adelsbrief André Falquets