##Background
When reusing references the backlinks in the reference lists to the individual reuses will be rendered as a list of symbols that work as an increasing index. As default there's a number amend to the number of the reference that's reused. E.g. `1.0`, `1.1`, `1.2.`
Wikis can customize how these symbols are generated though by creating an on wiki message. Most wikis do that to use letters for the backlinks E.g. `a` `b` `c`
When editors want to reuse a single reference a lot, there's the need in some cases to have a big amount of these symbols written out in that message. E.g. `aaa aab aac aad`.
##The Task
* We want to generate the needed markers by code and give communities the option to decide on the characters used with a simple setting.
* We set sensible defaults that depending on factors like e.g. the ContentLanguage.
* We want to implement a way how communities can set the Alphabet for the backlink symbols as replacement for the number defaults and want to ask the communities to set their favorite Alphabet using the provided setting if they don't want to fallback on the default Alphabets.
* This way we deprecate defaulting to a number system & get rid of the message key that is currently used to set that backlink symbol.
##Investigations
* {T383217}
* {T377918}
* {T381465}
* {T370882}
##Implementation steps
* {T383216}
* {T384291}
* {T384444}