Editing Z code (section)

== Distinct versions ==
There are at least three sets of Z&nbsp;codes.
:{|
|- style="vertical-align:top;"
| 1.
| One set of codes was originally developed by [[Cable & Wireless Worldwide|Cable & Wireless]] Ltd. (the Cable & Wireless Service Z&nbsp;code) for commercial communications in the early days of wire and radio communications.
:
Many of the old C&W codes are derived from [[mnemonics]]
: (ZAL = '''a'''lter wave'''l'''ength,<br/>ZAP = '''a'''ck '''p'''lease,<br/>ZSF = '''s'''end '''f'''aster, etc.)
:
The old C&W Z&nbsp;codes are not widely used today.
|- style="vertical-align:top;"
| 2.
| APCO{{clarify|date=November 2023}} also developed a system of Z&nbsp;codes.<ref>{{cite web |title=Standard Z&nbsp;Signals |website=APCO International Historical Collection (apcohistory.org) |url=http://www.apcohistory.org/apco-collection/search/profile/article/A28953}}</ref>
|- style="vertical-align:top;"
| 3.
| [[NATO]] forces independently developed a later set of Z&nbsp;codes for military use and inter-language needs. The NATO Z&nbsp;codes are still in use, and are published in the unclassified document [[ACP-131]].
|}

There are other sets of codes internally used by [[Russia]]'s military and other operating agencies.