[RFC PATCH v2 3/6] doc: Add namespace collision guidelines file

[Kenneth Lorber <keni@his.com>]

Add a file of guidelines to prevent the namespace collisions
mentioned in git help config without any guidance.

Signed-off-by: Kenneth Lorber <keni@his.com>
---
 .../technical/namespace-collisions.txt        | 72 +++++++++++++++++++
 1 file changed, 72 insertions(+)
 create mode 100644 Documentation/technical/namespace-collisions.txt

diff --git a/Documentation/technical/namespace-collisions.txt b/Documentation/technical/namespace-collisions.txt
new file mode 100644
index 0000000000..2a0cb312c5
--- /dev/null
+++ b/Documentation/technical/namespace-collisions.txt
@@ -0,0 +1,72 @@
+NAMESPACE COLLISIONS
+--------------------
+(Note that the recommendations in this section are under development
+and subject to change.  At this point they should be considered only
+suggestions.  If they do not work for your use case, or you are considering
+distributing your extension widely, please send a note to the mailing list.)
+
+Git uses identifiers in a number of different namespaces:
+
+* environment variables
+* files in $GIT_DIR
+* files in the working trees
+* config sections
+* hooks
+* attributes
+
+In order to reduce the chance of collisions between names Git uses
+and those used by other entities (users, groups, and extension authors),
+the following are recommended best practices.
+
+
+Names reserved to Git:
+
+* file or directory names ending with `.lock`
+* file or directory names starting with `.git`
+* filenames in $GIT_DIR
+* directory names in $GIT_DIR unless allowed by a rule below
+* environment variables starting with `GIT_`
+* configuration file sections unless allowed by a rule below
+* file or directory names in `$GIT_DIR/hooks` unless allowed by a rule below
+* attributes unless allowed by a rule below
+
+
+Names reserved for individual users:
+
+* The directory `$GIT_DIR/my`
+* Environment variables starting with `GIT_MY_`
+* Configuration section `my`
+* Files or directories in `$GIT_DIR/hooks` starting with `my_`
+* Attributes starting with `my_`
+
+Names reserved for individual repos:
+
+* The directory `$GIT_DIR/this`
+* Environment variables starting with `GIT_THIS_`
+* Configuration section `this`
+* Files or directories in `$GIT_DIR/hooks` starting with `this_`
+* Attributes starting with `this_`
+
+Names reserved for the lowest level group of people:
+
+* The directory `$GIT_DIR/our`
+* Environment variables starting with `GIT_OUR_`
+* Configuration section `our`
+* Files or directories in `$GIT_DIR/hooks` starting with `our_`
+* Attributes starting with `our_`
+
+Aliases
+~~~~~~~
+Aliases are a special case.  Users need to type them so they should be
+short, but there is no way to prevent such short names from colliding.
+So the documentation or installer should construct something like:
+
+  [alias]
+     test = !git my-test
+     my-test = !echo made it
+
+while detecting collisions for the short name.  Then users or local
+policy can deal with collisions on the short name.
+
+This is not meant to cover every possible use case - a policy that
+detailed would be ignored and thus of no use.  Please play nicely.
-- 
2.17.1