diff --git a/doc/source/admin/data_tables.md b/doc/source/admin/data_tables.md
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+# Tool data
+
+Galaxy stores tool data in the path defined by `tool_data_path` (by default `tool-data/`).
+It's possible to separate tool data of toolshed-installed tools by setting `shed_tool_data_path`.
+
+Tool data consists of:
+
+1. the actual data
+2. one or more `loc` files
+3. entries in a tool data table (config) file
+
+
+## History
+
+In order to understand the naming and structure of these three components it might be of advantage
+to look in the history. Tool data was organized in tabular `loc` that contained metadata and paths
+of the data. Those files were installed with the tool and could be accessed with the
+[`from_file`](https://docs.galaxyproject.org/en/master/dev/schema.html#from-file) mechanism from tools.
+Since each tool version had it's own `loc` file the maintenance was difficult. With tool data tables
+an additional abstraction layer was introduced that is used from tools via
+[`from_datatable`](https://docs.galaxyproject.org/en/master/dev/schema.html#from-data-table).
+
+## Tool data
+
+This is the actual data that is stored by default in `tool_data_path`. It may be favorable to store the
+actual tool data in a separate folder. For manually managed tool data this can be achieved by simply
+storing the data in another folder. For data that is added by data managers this can be achieved by
+setting `galaxy_data_manager_data_path`.
+
+## `loc` files
+
+In order to make tool data usable from Galaxy tools `loc` files are used. 
+Those are tabular (by default tab separated) files with the extension `.loc`.
+Besides the actual paths, the entries can contain IDs, names, or other metadata
+that can be used in tools to select reference data. The paths should be given as absolute paths,
+but can also be given relative to the Galaxy root dir.
+By default `loc` files are installed in `tool_data_path` (where also built-in `loc` files
+are stored). By setting `shed_tool_data_path` this can be separated.
+
+## Tool data tables
+
+The tool data tables that should be used in a Galaxy instance are listed
+in tool data table config files. In addition these contain metadata.
+
+Tool data table config files are XML files listing tool data table configurations:
+
+```xml
+<tables>
+    ....
+</tables>
+```
+
+An entry for a tool data looks like this
+
+```xml
+<table name="bwa_indexes_color" comment_char="#" allow_duplicate_entries="False">
+    <columns>value, dbkey, name, path</columns>
+    <file path="bwa_index_color.loc" />
+</table>
+```
+
+- `table`: `name`, `comment_char` (default `"#"`), `separator` (default `"\t"`), `allow_duplicate_entries` (default `True`), `empty_field_value` (default `""`)
+- `columns`: a comma separated list of column names
+- `file`: `path` (alternatively `url`, `from_config`)
+
+Tool data table entries for tools installed from a toolshed have an additional
+element `tool_shed_repository` and sub-tags `tool_shed`
+`repository_name`, `repository_owner`, `installed_changeset_revision`, e.g.:
+
+```xml
+<table name="plasmidfinder_database" comment_char="#">
+    <columns>value, name, date, path</columns>
+    <file path="/home/berntm/projects/galaxy/tool-data/toolshed.g2.bx.psu.edu/repos/iuc/plasmidfinder/7075b7a5441b/plasmidfinder_database.loc.sample"/>
+    <tool_shed_repository>
+        <tool_shed>toolshed.g2.bx.psu.edu</tool_shed>
+        <repository_name>plasmidfinder</repository_name>
+        <repository_owner>iuc</repository_owner>
+        <installed_changeset_revision>7075b7a5441b</installed_changeset_revision>
+    </tool_shed_repository>
+</table>
+```
+
+The file path points to a `loc` file and can be given relative (to the
+`tool_data_path`) or absolute. If a given relative path does not exist also the
+base name is checked (many tools use something like `tool-data/xyz.loc` and
+store example `loc` files in a `tool-data/` directory in the tool repository).
+Currently also `.loc.sample` may be used in case the specified `.loc` is absent.
+
+Galaxy uses two tool data table config files:
+
+- `tool_data_table_config_path`: by default `tool_data_table_conf.xml` in Galaxy's `config/` directory.
+- `shed_tool_data_table_config`: by default `shed_tool_data_table_conf.xml` in
+Galaxy's `config/` directory. This file lists all tool data tables of tools
+installed from a toolshed. Note that the entries are versioned, i.e. there is a
+separate entry for each tool and tool version.
+
+The tool data table config files can (and do) contain multiple entries for the same data table
+(identified by the same name). These content of the corresponding `loc` files are merged when
+they are loaded.
+
+When a new tool is installed that uses a data table a new entry is added to
+`shed_tool_data_table_config` and a `loc` file is placed in a versioned
+subdirectory in `tool_data_path` (in a subdirectory that has the name of the
+toolshed). By default this is `tool-data/toolshed.g2.bx.psu.edu/`. Note that
+these directories will also contain tool data table config files, but they are unused.
diff --git a/doc/source/admin/index.rst b/doc/source/admin/index.rst
index 2ae8d1af72a0..61ed7db63ba4 100644
--- a/doc/source/admin/index.rst
+++ b/doc/source/admin/index.rst
@@ -20,6 +20,7 @@ This documentation is in the midst of being ported and unified based on resource
    job_metrics
    authentication
    tool_panel
+   data_tables
    mq
    dependency_resolvers
    container_resolvers