This is per proxy which can also be abbreviated with pp or p.p. (According to Black's Law Dictionary. Even though there is no real equivalent, Prokura can be rendered an authorized officer, at least in American English.

Good luck!

That's how I usually translate this. It means the person signing the document on behalf of someone else has signature rights.

Per Schäfer, Wirtschaftsenglisch, this would be "per procuration".
See also the following:
If someone negotiates a physician's checks under a power of attorney, he/she typically prints the physician's name on the back of the check and enters his/her signature below, followed by "p.p." or "p.p.a." (for per procuration, per power of attorney, or power of attorney).
www.aamc.org/private/deans/afad/deanmemo/dm1999/99_48.htm


ppa.
(com) = per procuram
per procuration
(com) per Prokura, ppa. (ie, abbreviated: per pro)
per pro signature
(com) Prokura-Unterschrift f (eg, XY Bank, per pro John Doe)

HTH.

see also Dietl/Lorenz Dictionary of Commercial, Legal, and Political Terms

Here's some more information to thicken the soup:
According to DIN 5008 (Aufbau eines Geschäftsbriefes),
i.A. (im Auftrag) bezeichnet Einzelvollmacht, d.h. die Mitarbeiter/in, der/die unterschreibt ist in diesem einzelnen Fall dazu berechtigt.
i.V. (in Vollmacht, in Vertretung). Der/die Unterschreibende ist zu mehreren Rechtsgeschäften auf unbeschränkte Zeit berechtigt.
ppa. (per procura). Der/die Unterschreibende besitzt Prokura.

Bei mehreren Unterschriften steht die der/des Ranghöheren links.

I found the following definitions in West's Law & Commercial Dictionary in Five Languages:
Per procuration (per proc./, p.p.) By proxy; by one acting as an agent with special powers, as under a letter of attorney. These words give notice to all persons that the agent is acting under a special and limited authority. The phrase is commonly abbrerviated to per proc., or p.p. and is more used in the civil law and in England than in American law. A proxy or signature of a principal executed by an agent who discloses his role as agent on the document.
German: in Vollmacht, in Vertretung, (per) Prokura (Wertpapierzeichnung)

Procuration - Agency; proxy; the act of constituting another one's attorney in fact. The act by which one person gives power to another to act in his place, as he could do himself. Action under a power of attorney or other constitution of agency. Indorsing a bill or note "by procuration" is doing it as proxy for another or by his authority. The use of the word procuration (usually, per procuratione, or abbreviated to per proc. or p.p.) on a promissory note by an agent is notice that the agent has but a limited authority to sign.
German: Besorgung, Verschaffung, Vollmacht, Prokura, Stellvertretung.

Agency - Relation in which one person acts for or represents another by latter's authority ... The relation created by express or implied contract or by law, whereby one party delegates the transaction of some lawful business with more or less discretionary power to another ...
See also ...General agency, ...
German: Stellvertretung, Beveollmächtigung, Auftragsverhältnis

General agency - An agency which exists when there is a delegation to do all acts connected with a particular trade, business, or employment. It implies authority on the part of the agent to act without restriction or qualification in all matters relating to the business of his principal.
German: Generalvertretung, Prokura, Handlungsvollmacht.

General agent - one who is authorized to act for his principal in all matters concerning particular business or employment of particular nature.
German: allgemeiner Bevollmächtigter, Handlungsbevollmächtigter, Generalvertreter.

Handlungsvollmacht - Ger. commercial proxy; this proxy power may be given by any merchant and need not be explicit (e.g. by acquiescence). The commercial proxy is not entered in the commercial register. Signatures by a commercial proxy are customarily followed by the abbreviation i.V. ("in Vertretung").
German: Generalhandlungsvollmacht, Spezialhandlungsvollmacht, Anhandlungsvollmacht.

That's a lot of definitions. It would seem that the term general agent would most closely fit Prokurist in the sense as defined by Dan in his answer. But Prokurists are, to my knowledge, listed in the commercial registry.
Hope this helps more than it confuses! - Beth

Please correct me if I am wrong, but as far as I know, an agent, general agency, or general agent is by definition never an employee of her/his principal. Additionally, as far as I know, a Prokurist is always an employee of his employer (the person Who grants the Procura). If the two preceding sentences are correct then a Prokurist cannot be any sort of agent.

Margit - this is quite an important subject, please do not let Henry or Troy bulldoze you into grading the question till someone comes up with a really good answer. - Dan