What exactly does $(document).ready guarantee?

Running my (rather complex) JavaScript/jQuery application in Google's Chrome browser, it would appear that $(document).ready fires while some of the JavaScript files have not yet loaded.

The relevant code (simplified):

In my HTML file

<script>var httpRoot='../../../';var verifyLoad = {};</script>

<script src="../../../globalvars.js"></script>
<script src="../../../storagekeys.js"></script>
<script src="../../../geometry.js"></script>
<script src="../../../md5.js"></script>
<script src="../../../serialize.js"></script>
...
<script src="../../../main.js"></script>

As the last statement of each of the .js files except main.js:

verifyLoad.FOO = true; // where FOO is a property specific to the file

e.g.

verifyLoad.jquerySupplements = true; 

verifyLoad.serialize = true; 

In main.js:

$(document).ready(function() {
    function verifyLoadTest (scriptFileName, token) {
        if (!verifyLoad.hasOwnProperty(token)) {
            console.log(scriptFileName + ' not properly loaded'); 
        };
    };
    verifyLoadTest('globalvars.js', 'globalvars');
    verifyLoadTest('storagekeys.js', 'storagekeys');
    verifyLoadTest('geometry.js', 'geometry');
    verifyLoadTest('md5.js', 'geometry');
    verifyLoadTest('serialize.js', 'serialize');
    ...
}

Much to my amazement, I see some of these trigger. This does not match my understanding of $(document).ready. What am I missing?