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The Address tab is not directly editable when "Use Existing Address" is selected. Other addresses can be selected when a User clicks the button.
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From the Select an Existing Address form, a User can select any Address that has been entered into PCR-360. Clicking the button after an Address is selected, will update the Vendor.
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When "Create/Change Address" is selected, the Address tab becomes fully editable. If an Address is selected from the 
button, changes will be made to that entry. 
If an Address is created on a new Vendor, that addressed will be saved within PCR-360 so it can be used by others.