In principle, people may spell as they like; however, the final revision of the German spelling reform (2006) is arguably the generally preferred orthography. For example, the German-language news agencies AFP, APA, Dow Jones, dpa, epd, KNA, Reuters, and sid have adapted the spelling to post-reform rules (2007). The post-reform rules are obligatory in schools, in public administration, and in legislation. The transitional periods in Germany (2007), Belgium (2007), Austria (2008), South Tyrol (2008), Switzerland (2009), and Liechtenstein (2009) have passed. The pre-reform rules are to be considered incorrect in schools.
Many posts on German Language Stack Exchange initially contain spelling mistakes, i.e. spelling that is not conforming to the current spelling rules. Such spelling mistakes are regularly corrected by means of edits (cf. editing orthographic errors).
However, in some cases, the spelling of a word is not conforming to the current spelling rules, but it is conforming to pre-reform rules. Generally, it is not certain whether this is a mistake or intentional. At present, the handling of such occurrences is varying. Some posts are corrected while others are not. In rare unfortunate cases, a mixed spelling might result from inconsistent editing.
Such posts may confuse or mislead readers – particularly learners. Editors may be hesitant to make the necessary changes.
Therefore, it seems advisable to try to standardize a community guideline like the following draft:
When editing a post, any spelling of a word that is not conforming to the current spelling rules [but is conforming to pre-reform rules / –] [shall / should / may / need not / should not / shall not] be changed [to a spelling that is conforming to the current spelling rules / –].
(In your answer, feel free to use any combination of the above or any other wording.)
The verbal forms shall and shall not are used to indicate requirements strictly to be followed and from which no deviation is permitted.
The verbal forms should and should not are used to indicate that among several possibilities one is recommended as particularly suitable, without mentioning or excluding others, or that a certain course of action is preferred but not necessarily required, or that (in the negative form) a certain possibility or course of action is deprecated but not prohibited.
The verbal forms may and need not are used to indicate that a certain course of action is permissible.
In order to limit the scope, this discussion is not about
recommendations for words that have more than one permissible spelling (Fotograf / Photograph; allgemeingültig / allgemein gültig)
the differences of standard written German and colloquial or regional expressions. All expressions can be written in accordance to the current spelling rules.
the Swiss spelling of ss instead of ß
the spelling of quotations. Quotations should retain the spelling of the original.
the spelling of sample texts if a particular spelling is discussed or illustrated
the spelling of texts in case the author of the post somehow indicates or announces that the particular spelling is applied intentionally