A module definition can include a description statement. This is a form of documentation for the module that is embedded in the data structure.

The description statement must appear among the "declarative" statements at the beginning of the module definition body.

The description statement of a module takes the same form as the description statement of a procedure. The statement begins with the keyword description and is followed by one or more strings that, together, constitute the description of the module.

m := module()
    export set, get;
    local val;
    description "a register data structure";
    get := () -> val;
    set := proc(v) val := v end proc;
end module;

$m≔\mathbf{module}\left(\right)\mathbf{local}\mathrm{val}\;\mathbf{export}\mathrm{set}\,\mathrm{get}\;\mathbf{description}''a\; register\; data\; structure''\;\mathbf{end\; module}$