Element Descriptor

[Pradnya6]

Element Descriptor is not documented for calgary. Is there any latest documentation available? Prior to calgary I have used below code to get the choice table name from the field element.
var gr = new GlideRecord('cmdb_ci');
gr.get('254570386f7fcd0095d5f941be3ee48a');
var field = gr.getElement('os');
var ed = field.getED();
var choices = field.getChoices();
var choiceTable;
if (JSUtil.notNil(choices) && choices.size() > 0)
{
choiceTable = ed.getChoiceTable();
}

but some how this code is not working in calgary. Is there anything missing in the code? In calgary I am getting below error for above code.
Illegal access to method getChoiceTable() in class com.glide.db.ElementDescriptor

Please suggest.

[paulmorris]

var field = gr.getElement('os');
var choices = field.getChoices();

I had to write my own substitute function because it was at times only returning one or zero results, when it should have been returning multiple.