diff --git a/doc/src/02000-store.md b/doc/src/02000-store.md
index e9e503c9..ec978cc5 100644
--- a/doc/src/02000-store.md
+++ b/doc/src/02000-store.md
@@ -22,6 +22,11 @@ The contents of the header contain
    data goes to.
    The contents of these sections are edited via commandline calls or by the
    program implicitely and SHOULD NOT be edited by the user.
+   Modules of the program are free to store arbitrary data here.
+   If a module stores data in the header of a file it MUST do that in a
+   sub-section of the "imag" section, as TOML supports it.
+   The name of the subsection MUST BE the name of the module in lowercase
+   letters.
    The section MAY BE empty.
 1. Other OPTIONAL sections which are named and edited by the user. The program
    MUST NOT touch the contents of these sections, except explicitely asked by