Clarification - unless and/or if

[Rosenbaum, Thomas]

Hello,

I am using Ant 1.6.5 - can multiple properties be specified in the "if"
or "unless" attributes of a given target?  
    
        <available file="file.ext" property="prop1"/>
        <available file="file2.ext" property="prop2"/>
        <available file="file3.ext" property="prop3"/>
        <available file="file4.ext" property="prop4"/>

        <target name="blah" if="prop1,prop2"> ... </target>
        <target name="blahblah" unless="prop3,prop4"> ... </target>

If so, is the relationship an "or" or an "and"?

If this is not possible, what is the best practice for executing a
target if multiple conditions are met?  I could do the following, but I
end up creating all kinds of extra/throw-away properties:

        <condition property="exec-target1">
          <and>
            <available file="file.ext" property="prop1"/>
            <available file="file2.ext" property="prop2"/>
          </and>
        </condition>
        <condition property="do-not-exec-target1">
          <and>
            <available file="file3.ext" property="prop3"/>
            <available file="file4.ext" property="prop4"/>
          </and>
        </condition>
        <target name="blah" if="exec-target1"> ... </target>
        <target name="blahblah" unless="do-not-exec-target1"> ...
</target>

Can anyone help clear this up for me?
Many thanks!
- Tom