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README.md

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+# Lookup Tool [`doc_identifier`]
+
+## Description
+The lookup tool is an useful little helper which can be used to quickly learn more about about one's closer environment.
+It identifies blocks, dropped items and other objects and it shows extensive information about the item on which it is used,
+provided documentation is available.
+
+## How to use the lookup tool
+Punch any block or item about you wish to learn more about. This will open up the Documentation System entry of this particular
+item.
+The tool comes in two modes which are changed by a rightclick. In liquid mode (blue) this tool points to liquids as well
+while in solid mode (red) this is not the case. Liquid mode is required if you want to identify a liquid.
+
+## For modders
+If you want the tool to identify nodes and (dropped) items, you probably don't have to do anything, it is probably already
+supported. The only thing you have to make sure is that all pointable blocks and items have a help entry, which is already
+the case for most items, but you may want to do some testing on “tricky” items. Consult the documentation of the
+Documentation System [`doc`] and Item Documentation [`doc_items`] for getting the item documentation right.
+
+For the lookup tool to be able to work on custom objects/entities, you have to use the tiny API of this mod, see `API.md`.
+
+## License
+Everything in this mod is licensed under the “conditions” of the WTFPL.
+In other words: Just do what the fuck you want. Have fun! ;-)