diff --git a/metadata/dtd/glsa.dtd b/metadata/dtd/glsa.dtd
new file mode 100644
index 0000000000000..e3bf980dcf280
--- /dev/null
+++ b/metadata/dtd/glsa.dtd
@@ -0,0 +1,329 @@
+<!ELEMENT glsa  (title,synopsis,product,announced,revised,bug*,access?,affected,background?,description,impact,workaround,resolution,references,license?,metadata*)>
+<!ATTLIST glsa  id  CDATA   #REQUIRED>
+
+<!--
+    Element:      title
+    Description:  Provides a 4-5 word description about the advisory
+    Example:      <title>Buffer overflow vulnerability found in openssl-0.9.5</title>
+-->
+<!ELEMENT title  (#PCDATA)>
+
+<!--
+    Element:      synopsis
+    Description:  Small, to-the-point description about the GLSA
+
+    Example:  <synopsis>
+                  rsync has an exploitable buffer overflow that can lead to
+                  remote compromise
+              </synopsis>
+-->
+<!ELEMENT synopsis   (#PCDATA)>
+
+<!--
+    Element:      product
+    Description:  Defines what type of security announcement this is.
+
+                  Valid types are:
+                  - ebuild         A Portage-provided ebuild has a security
+                                   issue
+                  - informational  This GLSA is purely informational, no Gentoo
+                                   system is affected
+                  - infrastructure The security issue involves the Gentoo
+                                   infrastructure
+
+                  The text contains one keyword that defines the issue.
+                  Note: All type values but 'ebuild' are considered deprecated.
+
+    Example: <product type="ebuild">openssl</product>
+    Example: <product type="infrastructure">rsync mirror</product>
+-->
+<!ELEMENT product   (#PCDATA)>
+<!ATTLIST product   type    (ebuild|infrastructure|informational) #REQUIRED>
+
+<!--
+    Element:      announced
+    Description:  Date when the advisory is publicised
+                  The format must be "YYYY-mm-dd"
+
+    Example: <announced>2003-11-20</announced>
+-->
+<!ELEMENT announced (#PCDATA)>
+
+<!--
+    Element:      revised
+    Description:  Last revision date of the GLSA
+    Attribute:    @count: number of revisions
+
+    Example: <revised count="02">2003-11-20</revised>
+-->
+<!ELEMENT revised (#PCDATA)>
+<!ATTLIST revised count CDATA "01">
+
+<!--
+    Element:      bug
+    Description:  Number of the bug on bugs.gentoo.org, if any
+    Occurrence:    The bug element can occur 0, 1 or more times
+
+    Example: <bug>34200</bug>
+-->
+<!ELEMENT bug       (#PCDATA)>
+
+<!--
+    Element:      access
+    Description:  Type of access necessary to exploit the security issue
+                  This element should only be used when product@type = 'ebuild'
+    Occurrence:    The access element can occur 0 or 1 time
+
+    Example: <access>Remote</access>
+-->
+<!ELEMENT access    (#PCDATA)>
+
+<!--
+    Element:      affected
+    Description:  Describe what the affected subjects are.
+
+                  If product@type = 'ebuild', the child elements are 'package'
+                  If product@type = 'portage', the child elements are 'package'
+                  If product@type = 'infrastructure', the child elements are
+                  'service'
+
+-->
+<!ELEMENT affected  (package*|service*)>
+
+<!--
+    Element:      package
+    Description:  Provide all necessary information regarded the affected
+                  packages. It also contains information about the affected
+                  architectures, if automatic updates can be done and the update
+
+                  The "update" attribute contains the path to the non-vulnerable
+                  version of the package
+
+                  The "auto" attribute contains either "yes" or "no" and tells
+                  Portage that the package can be updated automatically (to be
+                  implemented) without further user interaction
+
+                  The "arch" attribute contains either the architecture (as used
+                  by ACCEPT_KEYWORDS) or the "*" value (in case all
+                  architectures are affected)
+
+    Occurrence:   The package element can occur 0, 1 or more times
+    Example:      <package name="dev-libs/openssl" auto="yes" arch="*">
+                    <vulnerable range="lt">0.9.6k</vulnerable>
+                    <unaffected range="gt">0.9.6k</unaffected>
+                  </package>
+-->
+<!ELEMENT package (vulnerable|unaffected)*>
+<!ATTLIST package name      CDATA           #REQUIRED
+                  auto      (yes|no)    #REQUIRED
+                  arch      CDATA           #REQUIRED>
+
+<!--
+    Element:      vulnerable
+    Description:  Version of the vulnerable package. Can be a range too
+-->
+<!ELEMENT vulnerable (#PCDATA)>
+<!ATTLIST vulnerable range      (le|lt|eq|gt|ge|rlt|rle|rgt|rge)      #REQUIRED
+                     slot       CDATA                 "*">
+
+<!--
+    Element:      unaffected
+    Description:  Version of the fixed (or unaffected) package. In case the
+                  package is superseded by another package, you need to
+                  define that package using the "name" attribute.
+
+                  The r* range information is revision-specific. For instance,
+                  rge foo-1.2.3-r4  ==  >=foo-1.2.3-r4 && <foo-1.2.4
+
+    Example:
+                  <unaffected range="gt" name="foobar">2.0.0</unaffected>
+-->
+<!ELEMENT unaffected (#PCDATA)>
+<!ATTLIST unaffected range      (le|lt|eq|gt|ge|rlt|rle|rgt|rge)      #REQUIRED
+                     slot       CDATA                 "*"
+                     name       CDATA                 #IMPLIED>
+
+<!--
+    Element:      service
+    Description:  Provide information about the Gentoo services that are
+                  affected by the security advisory. Portage must be able
+                  to parse this information to make decisions (for instance,
+                  ignore an rsync server or a certain distfiles mirror).
+
+                  The type attribute can be one of "rsync", "web", "mirror".
+
+                  The fixed attribute (denoting if the problem has been solved)
+                  can be one of "yes" or "no". If not used, the default value is
+                  "no".
+
+    Occurrence:   The service element can occur 0, 1 or more times
+    Example: <service type="rsync">rsync://rsync.someserver.tld/gentoo-portage</service>
+-->
+<!ELEMENT service (#PCDATA)>
+<!ATTLIST service type (rsync|web|mirror) #REQUIRED
+                  fixed (yes|no)          #IMPLIED>
+
+<!--
+    Element:      uri
+    Description:  Link to the organisation involved in releasing the advisory
+    Occurrence:   The uri element can occur 0, 1 or more times
+
+    Example:      <uri link="http://www.cert.org">CERT</uri>
+-->
+<!ELEMENT uri       (#PCDATA)>
+<!ATTLIST uri     link  CDATA   #IMPLIED>
+
+<!--
+    Element:      mail
+    Description:  Mail address of the people involved in releasing the advisory
+    Occurrence:   The mail element can occur 0, 1 or more times
+
+    Example:      <mail link="some@person.com">Some Person</mail>
+-->
+<!ELEMENT mail      (#PCDATA)>
+<!ATTLIST mail    link  CDATA   #REQUIRED>
+
+<!--
+    Element:      p
+    Description:  Plain text
+    Occurrence:   The "p" element can occur 0, 1 or more times and can contain
+                  links or addresses
+
+    Example:      <p>Please update your system</p>
+-->
+<!ELEMENT p (#PCDATA|mail|uri|b|i|br)*>
+
+<!--
+    Element:      code
+    Description:  The code element contains text that should preserve whitespace
+                  and is therefore useful for code listings or commands
+
+    Example:      <code>emerge sync</code>
+-->
+<!ELEMENT code (#PCDATA)>
+
+<!--
+    Element:      background
+    Description:  Provides a background of the affected package(s)/service(s)
+                  The background element contains only "<p>"s in which the text
+                  is placed
+
+-->
+<!ELEMENT background  (p|ul|ol)*>
+
+<!--
+    Element:      description
+    Description:  Provides a description about the security issue
+                  The description element contains only "<p>"s.
+-->
+<!ELEMENT description (p|ul|ol|code)*>
+
+<!--
+    Element:      impact
+    Description:  Provides information about the impact that the security issue
+                  can have
+
+                  The "impact" element contains only "<p>"s.
+
+                  The type element gives a short term, such as
+                  "Denial of Service", "Buffer Overflow", ...
+
+-->
+<!ELEMENT impact    (p|ul|ol)*>
+<!ATTLIST impact    type    CDATA   #REQUIRED>
+
+<!--
+    Element:      workaround
+    Description:  Provides information about how the security issue can be
+                  (temporarily) resolved through a work-around
+
+                  The "workaround" element contains only "<p>"s and "<code>"s.
+-->
+<!ELEMENT workaround    (p|code|ul|ol)*>
+
+<!--
+    Element:      resolution
+    Description:  Provides information about how the security issue can be
+                  resolved.
+
+                  The "resolution" element contains only "<p>"s and "<code>"s.
+-->
+<!ELEMENT resolution  (p|code|ul|ol)*>
+
+<!--
+    Element:      references
+    Description:  Provides links to resources / references available online.
+
+                  The "reference" element contains only "<uri>"s.
+-->
+<!ELEMENT references    (uri*)>
+
+<!--
+    Element:      ul
+    Description:  Add an unnumbered listing; can only contain <li>'s
+-->
+<!ELEMENT ul            (li*)>
+
+<!--
+    Element:      ol
+    Description:  Add a numbered listing; can only contain <li>'s
+-->
+<!ELEMENT ol            (li*)>
+
+<!--
+    Element:      li
+    Description:  Element of a listing
+
+    Example:    <ul>
+                  <li>This is element one</li>
+                  <li>This is a second element</li>
+                </ul>
+-->
+<!ELEMENT li            (#PCDATA)>
+
+<!--
+    Element:      b
+    Description:  Bold text
+
+    Example:    <b>this is bold</b>
+-->
+<!ELEMENT b             (#PCDATA)>
+
+<!--
+    Element:      i
+    Description:  Input text (blue)
+
+    Example:      The user has to type in <i>ls</i> to see.
+-->
+<!ELEMENT i             (#PCDATA)>
+
+<!--
+    Element:      br
+    Description:  hard line break
+
+    Example:      And then: <br/>
+                  KABLAM!
+-->
+<!ELEMENT br            (#PCDATA)>
+
+<!--
+    Element:      license
+    Description:  Add license information
+
+    Example:      <license/>
+-->
+<!ELEMENT license       (EMPTY)>
+
+<!--
+    Element:      metadata
+    Description:  Metadata information for GLSAMaker
+
+    Example:      <metadata tag="approved">Level 1</metadata>
+
+    On request of plasmaroo, metadata can contain all elements again.
+-->
+<!ELEMENT metadata  (#PCDATA|metadata)*>
+<!ATTLIST metadata tag      CDATA #REQUIRED
+                   revision CDATA #IMPLIED
+                   author   CDATA #IMPLIED
+                   timestamp CDATA #IMPLIED>
diff --git a/metadata/dtd/metadata.dtd b/metadata/dtd/metadata.dtd
new file mode 100644
index 0000000000000..9aab14de3f535
--- /dev/null
+++ b/metadata/dtd/metadata.dtd
@@ -0,0 +1,97 @@
+<!-- Metadata for a category -->
+<!ELEMENT catmetadata ( (longdescription)* )>
+
+<!-- Metadata for a package -->
+<!ELEMENT pkgmetadata ( (maintainer|longdescription|slots|stabilize-allarches|use|upstream)* )>
+
+  <!-- One tag for each maintainer of a package, multiple allowed-->
+  <!ELEMENT maintainer (email|name|description)+>
+  <!-- type attribute determines whether the maintainer is a person or a project.
+    Unknown is added to handle <maintainer/>s in <upstream/>s. Using it (or no
+    explicit type) for Gentoo maintainers is prohibited. -->
+  <!ATTLIST maintainer type (person|project|unknown) "unknown">
+  <!-- proxied attribute determines whether the maintainer is a proxied
+    maintainer (yes), regular dev (no) or a proxy for somebody (proxy). It is
+    valid only for Gentoo maintainers. -->
+  <!ATTLIST maintainer proxied (yes|no|proxy) "no">
+
+  <!-- A long description of the package in freetext-->
+  <!ELEMENT longdescription (#PCDATA|pkg|cat)* >
+
+  <!-- A description of the packages SLOTs -->
+  <!ELEMENT slots ((slot)*,subslots?) >
+    <!-- A particular SLOT -->
+    <!ELEMENT slot (#PCDATA)* >
+      <!-- name attribute holds the name of the SLOT, for sub-SLOTS
+      use the subslots element. A slot name of '*' can be used to
+      indicate a single description applying to all the slots in which
+      case no other <slot/> elements may be present. -->
+      <!ATTLIST slot name CDATA #REQUIRED >
+    <!-- The meaning of sub-SLOTs for the whole package -->
+    <!ELEMENT subslots (#PCDATA)* >
+
+  <!-- whether it's possible to stabilize ALLARCHES -->
+  <!ELEMENT stabilize-allarches EMPTY>
+
+  <!-- description of what this USE flag does for this package -->
+  <!ELEMENT use (flag)* >
+    <!ELEMENT flag (#PCDATA|pkg|cat)* >
+      <!-- name attribute holds the name of the USE flag -->
+      <!ATTLIST flag name CDATA #REQUIRED >
+
+  <!-- upstream metadata information (maintainers, upstream docs,..) -->
+  <!ELEMENT upstream (maintainer|changelog|doc|bugs-to|remote-id)* >
+    <!-- Due to the limitation of DTD this will also allow a status
+      attribute for the package maintainer element. Please note that
+      the usage of the status attribute is nevertheless _only_ allowed
+      in the upstream maintainer element. -->
+    <!ATTLIST maintainer status (active|inactive|unknown) "unknown" >
+    <!-- URL where the upstream changelog can be found -->
+    <!ELEMENT changelog (#PCDATA)>
+    <!-- URL where the location of the upstream documentation can be found -->
+    <!ELEMENT doc (#PCDATA)>
+      <!ATTLIST doc lang CDATA "en" >
+    <!-- location where to report bugs
+      (may also be an email address prefixed with mailto:) -->
+    <!ELEMENT bugs-to (#PCDATA)>
+    <!-- specify a type of package identification tracker -->
+    <!ELEMENT remote-id (#PCDATA)>
+      <!ATTLIST remote-id type (bitbucket|codeberg|cpan|cpan-module|cpe|cran|ctan|freedesktop-gitlab|gentoo|github|gitlab|gnome-gitlab|google-code|hackage|heptapod|kde-invent|launchpad|osdn|pear|pecl|pypi|rubygems|savannah|savannah-nongnu|sourceforge|sourcehut|vim) #REQUIRED>
+
+  <!-- category/package information for cross-linking in descriptions
+    and useflag descriptions -->
+  <!ELEMENT pkg (#PCDATA) >
+  <!ELEMENT cat (#PCDATA) >
+
+<!-- Common attributes -->
+
+<!-- the lang attribute, specifies the language of this tag in the
+  form of an IETF (BCP 47) language tag. This is only useful for
+  descriptions of various kinds. If a tag with this attribute is
+  included there must be a description in the default language "en" -->
+  <!ATTLIST description lang CDATA "en" >
+  <!ATTLIST longdescription lang CDATA "en" >
+  <!ATTLIST slots lang CDATA "en" >
+  <!ATTLIST use lang CDATA "en" >
+
+<!-- The restrict attribute, this attribute specifies restrictions on
+  the applicability of tags on versions. The format of this attribute is
+  equal to the format of DEPEND lines in ebuilds. Only package
+  dependency specifications conforming to EAPI=0 syntax are allowed.
+  The dependency specification may only contain references to the
+  package itself and no other package.
+
+  For required tags, there must be either an unrestricted version, or a
+  version that is default restricted. -->
+  <!ATTLIST maintainer restrict CDATA #IMPLIED >
+  <!ATTLIST longdescription restrict CDATA #IMPLIED >
+  <!ATTLIST flag restrict CDATA #IMPLIED >
+  <!ATTLIST stabilize-allarches restrict CDATA #IMPLIED >
+
+<!-- standard parts -->
+<!-- an email address -->
+<!ELEMENT email (#PCDATA) >
+<!-- the name of a person (maintainer, contributor) -->
+<!ELEMENT name (#PCDATA) >
+<!-- A description of a maintainer or change -->
+<!ELEMENT description (#PCDATA) >
diff --git a/metadata/dtd/mirrors.dtd b/metadata/dtd/mirrors.dtd
new file mode 100644
index 0000000000000..9fc6223601947
--- /dev/null
+++ b/metadata/dtd/mirrors.dtd
@@ -0,0 +1,67 @@
+<!-- This file is used for keeping the new mirrors.xml file -->
+
+<!--
+  element: mirrors
+  description: A set of mirrorgroups
+  example: <mirrors>
+             <mirrorgroup country="US" region="North America">
+               ...
+             </mirrorgroup>
+             ...
+           </mirrors>
+-->
+
+<!ELEMENT mirrors (mirrorgroup*)>
+
+<!--
+  element: mirrorgroup
+  description: Group mirrors by region and country.
+  example: <mirrorgroup region="South America" country="BZ">
+             <mirror>
+               ...
+             </mirror>
+             ...
+           </mirrorgroup
+-->
+
+<!ELEMENT mirrorgroup (mirror*)>
+<!ATTLIST mirrorgroup region CDATA #REQUIRED
+                      country CDATA #REQUIRED
+                      countryname CDATA #IMPLIED>
+<!--
+  element: mirror
+  description: One per mirror; name the mirror and provide one or more uris
+  optionally: provide GPS coordinates, a city and a bug id.
+  example: <mirror city="Corvallis"
+                   coordinates="44.5646,-123.2620"
+                   gentoo-bug="12345">
+             <name>OSU Open Source Lab</name>
+             <uri protocol="http">http://gentoo.osuosl.org/</uri>
+             <uri protocol="ftp">ftp://gentoo.osuosl.org/</uri>
+           </mirror>
+-->
+<!ELEMENT mirror (name, uri+)>
+<!ATTLIST mirror
+    city CDATA #IMPLIED
+    coordinates CDATA #IMPLIED
+    gentoo-bug CDATA #IMPLIED>
+
+<!--
+  element: name
+  description: Name of the mirror
+  note: Do not include a country and protocol pair, "(USA/http)" as they will
+        be built by the XSL.
+  example: <name>OSU Open Source Lab</name>
+-->
+<!ELEMENT name (#PCDATA)>
+
+<!--
+  element: uri
+  description: A Uniform Resource Locator for a given mirror
+  example: <uri protocol='http' ipv4='y' ipv6='y'>http://gentoo.osuosl.org/</uri>
+-->
+<!ELEMENT uri (#PCDATA)>
+<!ATTLIST uri ipv4 (Y|y|N|n) "y"
+              ipv6 (Y|y|N|n) "n"
+              partial (Y|y|N|n) "n"
+              protocol (http|ftp|rsync) "http">
diff --git a/metadata/dtd/projects.dtd b/metadata/dtd/projects.dtd
new file mode 100644
index 0000000000000..6ce0544bcfbe6
--- /dev/null
+++ b/metadata/dtd/projects.dtd
@@ -0,0 +1,26 @@
+<!ELEMENT projects (project)*>
+<!-- A project (identified by email address) -->
+<!ELEMENT project (email,name,url,description,subproject*,member*)>
+<!-- Contact e-mail address of a project or a project member -->
+<!ELEMENT email (#PCDATA)>
+<!-- Name of a project or a project member -->
+<!ELEMENT name (#PCDATA)>
+<!-- URL of the project homepage -->
+<!ELEMENT url (#PCDATA)>
+<!-- Description of the project -->
+<!ELEMENT description (#PCDATA)>
+<!-- Project member -->
+<!ELEMENT member (email,name,role)>
+<!-- is-lead="1" indicates that the member is the project's lead -->
+<!ATTLIST member
+          is-lead (0|1) "0">
+<!-- Project member role -->
+<!ELEMENT role (#PCDATA)>
+<!-- Subproject of a project -->
+<!ELEMENT subproject (#PCDATA)>
+<!-- inherit-members="1" indicates that the project inherits members
+	from the subproject -->
+<!-- ref="" references the subproject by the contact e-mail address -->
+<!ATTLIST subproject
+          inherit-members (0|1) "0"
+          ref CDATA #REQUIRED>
diff --git a/metadata/dtd/repositories.dtd b/metadata/dtd/repositories.dtd
new file mode 100644
index 0000000000000..6fa353f04433a
--- /dev/null
+++ b/metadata/dtd/repositories.dtd
@@ -0,0 +1,64 @@
+<!-- Used by [gentoo]/xml/htdocs/proj/en/overlays/repositories.xml -->
+<!--
+The source copy and history of this file is available from
+https://gitweb.gentoo.org/proj/repositories-xml-format.git/
+-->
+<!--
+    Gentoo repositories.xml DTD 1.0
+
+    Modelling by
+      Robert Buchholz <rbu@gentoo.org>
+      Sebastian Pipping <sebastian@pipping.org>
+      Mounir Lamouri <volkmar@gentoo.org>
+      Tiziano Müller <dev-zero@gentoo.org>
+
+    Copyright 1999-2015 Gentoo Foundation
+    Distributed under the terms of the GNU General Public License v2 or later
+-->
+<!ELEMENT repositories (repo)*>
+<!ATTLIST repositories
+  xmlns CDATA #FIXED ''
+  version CDATA #FIXED '1.0'>
+
+<!ELEMENT repo (name,(description)+,(longdescription)*,(homepage)?,(owner)+,(source)+,(feed)*)>
+<!ATTLIST repo
+  xmlns CDATA #FIXED ''
+  priority CDATA #IMPLIED
+  quality (core|stable|testing|experimental|graveyard) #REQUIRED
+  status (official|unofficial) #REQUIRED>
+
+<!ELEMENT name (#PCDATA)>
+<!ATTLIST name
+  xmlns CDATA #FIXED ''>
+
+<!ELEMENT description (#PCDATA)>
+<!ATTLIST description
+  xmlns CDATA #FIXED ''
+  lang CDATA #IMPLIED>
+
+<!ELEMENT longdescription (#PCDATA)>
+<!ATTLIST longdescription
+  xmlns CDATA #FIXED ''
+  lang CDATA #IMPLIED>
+
+<!ELEMENT homepage (#PCDATA)>
+<!ATTLIST homepage
+  xmlns CDATA #FIXED ''>
+
+<!ELEMENT owner (email,(name)?)>
+<!ATTLIST owner
+  xmlns CDATA #FIXED ''
+  type (project|person) #IMPLIED>
+
+<!ELEMENT source (#PCDATA)>
+<!ATTLIST source
+  xmlns CDATA #FIXED ''
+  type (bzr|cvs|darcs|git|mercurial|rsync|svn|tar) #REQUIRED>
+
+<!ELEMENT feed (#PCDATA)>
+<!ATTLIST feed
+  xmlns CDATA #FIXED ''>
+
+<!ELEMENT email (#PCDATA)>
+<!ATTLIST email
+  xmlns CDATA #FIXED ''>
diff --git a/metadata/dtd/userinfo.dtd b/metadata/dtd/userinfo.dtd
new file mode 100644
index 0000000000000..8058c7d792958
--- /dev/null
+++ b/metadata/dtd/userinfo.dtd
@@ -0,0 +1,23 @@
+<!ELEMENT userlist (user+)>
+<!ELEMENT user (realname, pgpkey+, alias*, email+, joined*, retired*, status?, roles?, location?) >
+  <!ATTLIST user username ID #REQUIRED>
+  <!ELEMENT realname (firstname,familyname)>
+    <!ATTLIST realname fullname CDATA #IMPLIED>
+    <!ELEMENT firstname (#PCDATA) >
+    <!ELEMENT familyname (#PCDATA) >
+      <!ATTLIST familyname sort CDATA #IMPLIED>
+  <!ELEMENT pgpkey (#PCDATA)>
+  <!ELEMENT alias (#PCDATA)>
+  <!ELEMENT email (#PCDATA)>
+
+  <!-- all dates should be YYYY-MM-DD - eg '2006-11-22' -->
+  <!ELEMENT joined (#PCDATA)>
+  <!ELEMENT retired (#PCDATA)>
+
+  <!ELEMENT status (#PCDATA)>
+  <!ELEMENT roles (#PCDATA)>
+  <!-- Location is the string displayed on the webpage -->
+  <!ELEMENT location (#PCDATA)>
+      <!-- signed decimal numbers. degrees north/east. -->
+      <!ATTLIST location latitude  CDATA #IMPLIED
+                         longitude CDATA #IMPLIED>