I suppose the format of the properties could look something like this:

<properties>
        <property>
            <name>maven-dependencies</name>
            <value>org.springframework:spring-webmvc:2.5.6.SEC03:jar</value>
        </property>
        <property>
            <name>maven-repositories</name>
            <value>http://repo1.maven.org/maven2/</value>
        </property>
    </properties>

where maven-repositories is a || separated list of repository urls required. central repository can be omitted.
maven-dependencies is a || separated list of dependency declarations, with the following pattern:
groupId:artifactId:version:classifier:type where classifier can be omitted resulting in groupId:artifactId:version:type

I'm not entirely happy with the separator pattern, but I don't see a way to have one property per dependency, unless we come with some sort of numbering scheme.

we might need also maven-legacy-repositories or format:url in repositories value to denote the maven1 or maven2 repository format. (default vs legacy)

(In reply to comment #1)
>         <property>
>             <name>maven-repositories</name>
>             <value>http://repo1.maven.org/maven2/</value>
>         </property>

Optional, I presume, and ought to be discouraged in favor of using artifacts in Central.

> || separated list of repository urls

' ' (SPACE) is a perfectly good separator for URLs. Same for GAVs.

"space" it is.

http://hg.netbeans.org/core-main/rev/09bff123568f

repotype:repourl is the pattern for repositories, central should be omitted.

Integrated into 'main-golden', will be available in build *201207201342* on http://bits.netbeans.org/dev/nightly/ (upload may still be in progress)
Changeset: http://hg.netbeans.org/main-golden/rev/09bff123568f
User: Milos Kleint <mkleint@netbeans.org>
Log: #209602 use properties rather than maven-pom volume to define the maven coordinates representing the library