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+# Generating multiple sites
+
+In order to support subset as a blog (see [#222](https://github.com/srid/neuron/issues/222)), we need the ability to configure multiple sites (e.g. one for your local notes and another for your blog) as well as the ability to publish only a subset of the Zettelkasten (e.g. your blog might only publish zettels tagged `blog`).
+
+## Filtering zettels while generating
+
+For this, we add a new config parameter `filterZettels` with the same syntax as we use for queries. Only zettel matching this query will be included while generating the site.
+
+## Multiple site configuration
+
+To configure multiple sites, we modify the existing configuration format.
+
+- At the top level, we have the following fields:
+
+|Field name|Description|
+|---|---|
+|**`minVersion`**|The minimum neuron version your site must be generated with. (optional)|
+|**`sites`**|A mapping of site identifier and site config.|
+
+- Each site config can have these optional parameters:
+
+|Field name|Description|
+|---|---|
+|**`siteTitle`**|Your Neuron site's title|
+|**`author`**|Author name|
+|**`siteBaseUrl`**|The base URL of your published Neuron site. Setting the base URL will enable [breadcrumbs](https://developers.google.com/search/docs/data-types/breadcrumb) in your site's structured data|
+|**`theme`**|Color scheme to use for your site. Value must be [one of the color names](https://semantic-ui.com/usage/theming.html#sitewide-defaults) supported by SemanticUI.|
+|**`aliases`**|Setup custom redirects in the statically generated site.|
+|**`editUrl`**|The URL (without the zettel filename) to edit zettels.|
+|**`formats`**|Formats other than Markdown to use; eg: `["markdown", "org"]`|
+|**`filterZettels`**|Query used to filter the zettels|
+
+For backwards compatability, in absence of the `sites` field, we conside a single site implictly named `default`. All fields that are allowed at the top level (in the new config format) as well as for individual site config can be used here.
+
+## Example
+```dhall
+{ minVersion = "0.4.0.0"
+, sites =
+  { default =
+    { siteTitle = "My local Zettelkasten"
+    , siteBaseUrl = Some "127.0.0.1:8080"
+    , theme = "brown"
+    }
+  , blog =
+    { siteTitle = "My blog"
+    , siteBaseUrl = Some "https://somecollege.edu/~john/neuron"
+    , theme = "blue"
+    , aliases = [ "thesis-portal:2011402" ]
+    , editUrl = Some "https://github.com/john/website/edit/master/notes/"
+    , filterZettels = "<z:zettels?tag=blog>"
+    }
+  }
+}
+```