diff --git a/doc/package-system.txt b/doc/package-system.txt
index bfe6c78..2e126f3 100644
--- a/doc/package-system.txt
+++ b/doc/package-system.txt
@@ -13,7 +13,7 @@ comprise the system are as follows.
 | checksums        | DSL [3]  | No         | No       | No          | No [1]   |
 | depends          | DSL [3]  | No         | Yes      | Yes         | No       |
 | sources          | DSL [3]  | No         | Yes      | Yes         | No       |
-| version          | DSL [3]  | No         | No       | No          | Yes      |
+| version          | DSL [3]  | No         | [4]      | [4]         | Yes      |
 |                  |          |            |          |             |          |
 | pre-remove       | Any      | Yes [2]    | N/A      | N/A         | No       |
 | post-install     | Any      | Yes [2]    | N/A      | N/A         | No       |
@@ -32,6 +32,9 @@ rows by newline and columns by whitespace.
 [3] The file's format is a domain specific language with its own rules.
     https://en.wikipedia.org/wiki/Domain-specific_language
 
+[4] Tooling should only read the first line of the version file. Any lines
+    following should be ignored (allowing one to store arbitrary information).
+
 
 [0.0] Index
 ________________________________________________________________________________