Procedures and abbreviations The Heer and Luftwaffe transmitted their messages always in five-letter group. To make cryptanalysis harder, it was forbidden to use more than 250 characters in a single message. Longer messages were divided into several parts, each part using its own message key. The Enigma machine could process letters only. Therefore, numbers were written out and punctuations were replaced by rare letter combinations. The Wehrmacht used the following abbreviations:
KLAM = Parenthesis ZZ = Comma X = Full stop (end of sentence) YY = Point or dot X****X = Inverted commas
Question mark (Fragezeichen in German) was usually abbreviated to FRAGE, FRAGEZ or FRAQ. Foreign names, places, etc. are delimited twice by "X", as in XPARISXPARISX or XFEUERSTEINX. The letters CH were written as Q. ACHT became AQT, RICHTUNG became RIQTUNG.
Numbers were written out as NULL EINZ ZWO DREI VIER FUNF SEQS SIEBEN AQT NEUN
It was prohibited to encipher the word "NULL" several times in succession, so they used CENTA (00), MILLE (000) and MYRIA (0000). Some examples: 200 = ZWO CENTA, 00780 = CENTA SIEBEN AQT NULL.
The Kriegsmarine formatted their messages in four-letter groups. They used the following abbreviations:
X = Period Y = Comma UD = Question Mark XX = Colon YY = Dash/Hyphen/Slant KK**KK = Parenthesis J******J = Stress Mark
You could spell out the number or use roman numerals. I prefer the roman numeral idea because it saves message space, however, anyone you are sending messages to needs to know you are using roman numerals.