Re-order doc chapters

Change-Id: I44cf2054fa06816480e26fc19b45c6f8a464a708
Signed-off-by: Sebastien Douheret <sebastien.douheret@iot.bzh>

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+The permissions
+===============
+
+
+Permission's names
+------------------
+
+The proposal here is to specify a naming scheme for permissions
+that allows the system to be as stateless as possible. The current
+specification includes in the naming of permissions either
+the name of the bound binding when existing and the level of the
+permission itself. Doing this, there is no real need for the
+framework to keep installed permissions in a database.
+
+The permission names are [URN][URN] of the form:
+
+	urn:AGL:permission:<api>:<level>:<hierarchical-name>
+
+where "AGL" is the NID (the namespace identifier) dedicated to
+AGL (note: a RFC should be produced to standardize this name space).
+
+The permission names are made of NSS (the namespace specific string)
+starting with "permission:" and followed by colon separated
+fields. The 2 first fields are `<api>` and `<level>` and the remaining
+fields are grouped to form the `<hierarchical-name>`.
+
+	<api> ::= [ <pname> ]
+
+	<pname> ::= 1*<pchars>
+
+	<pchars> ::= <upper> | <lower> | <number> | <extra>
+
+	<extra> ::= "-" | "." | "_" | "@"
+
+The field `<api>` can be made of any valid character for NSS except
+the characters colon and star (:*). This field designates the api
+providing the permission. This scheme is used to deduce binding requirements
+from permission requirements. The field `<api>` can be the empty
+string when the permission is defined by the AGL system itself.
+
+[PROPOSAL 1] The field `<api>` if starting with the character "@" represents
+a transversal/cross permission not bound to any binding.
+
+[PROPOSAL 2]The field `<api>` if starting with the 2 characters "@@"
+in addition to a permission not bound to any binding, represents a
+permission that must be set at installation and that can not be
+revoked later.
+
+	<level> ::= 1*<lower>
+
+The field `<level>` is made only of letters in lower case.
+The field `<level>` can only take some predefined values:
+
+ - system
+ - platform
+ - partner
+ - tiers
+ - owner
+ - public
+
+The field `<hierarchical-name>` is made of `<pname>` separated
+by colons.
+
+	<hierarchical-name> ::= <pname> 0*(":" <pname>)
+
+The names at left are hierarchically grouping the
+names at right. This hierarchical behaviour is intended to
+be used to request permissions using hierarchical grouping.
+
+
+Permission value
+----------------
+
+In some case, it could be worth to add a value to a permission.
+
+Currently, the framework allows it for permissions linked to
+systemd. But this not currently used.
+
+Conversely, permissions linked to cynara can't carry data
+except in their name.
+
+Thus to have a simple and cleaner model, it is better to forbid
+attachement of value to permission.
+
+
+Example of permissions
+----------------------
+
+Here is a list of some possible permissions. These
+permissions are available the 17th of March 2017. 
+
+ - urn:AGL:permission::platform:no-oom
+
+   Set OOMScoreAdjust=-500 to keep the out-of-memory
+   killer away.
+
+ - urn:AGL:permission::partner:real-time
+
+   Set IOSchedulingClass=realtime to give to the process
+   realtime scheduling.
+
+   Conversely, not having this permission set RestrictRealtime=on
+   to forbid realtime features.
+
+ - urn:AGL:permission::public:display
+
+   Adds the group "display" to the list of supplementary groups
+   of the process.
+
+ - urn:AGL:permission::public:syscall:clock
+
+   Without this permission SystemCallFilter=~@clock is set to
+   forfid call to clock.
+
+ - urn:AGL:permission::public:no-htdocs
+
+   The http directory served is not "htdocs" but "."
+
+ - urn:AGL:permission::public:applications:read
+
+   Allows to read data of installed applications (and to
+   access icons).
+
+ - urn:AGL:permission::partner:service:no-ws
+
+   Forbids services to provide its API through websocket.
+
+ - urn:AGL:permission::partner:service:no-dbus
+
+   Forbids services to provide its API through D-Bus.
+
+ - urn:AGL:permission::system:run-by-default
+
+   Starts automatically the application. Example: home-screen.
+
+ - http://tizen.org/privilege/internal/dbus
+
+   Permission to use D-Bus.
+
+
+[URN]: https://tools.ietf.org/rfc/rfc2141.txt "RFC 2141: URN Syntax"
+