Use this for:

 1. Apps/Scripts/Libraries that **require/use obsolete API's**.  <sup><sub>EG: Stack Exchange API version 1.0</sub></sup>
 2.  Apps/Scripts/Libraries that **operate on/for sites or features that no longer exist.**
 3.  Apps/Scripts/Libraries that have **websites and/or source-code that has disappeared and is not salvageable.**
 4.  Apps/Scripts/Libraries that **the owner/developer otherwise indicates is obsolete and/or serviceable.**
 5. [tag:bug]s or [tag:feature-request]s that apply to **deprecated API versions or deprecated site features.**

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###See also: https://stackapps.com/questions/7983/what-should-we-do-about-dead-listings