Using "mmddyyhm" in a PDF as a project number

[DaveMartz2]

I've created a PDF with a field to be used as a unique project number. The filed is being populated with the date and time with this java script: 

// get the current date and time
var d = new Date();

this.getField("UniqueNumber").value = util.printd("yymmddHHMM", d);

The problem I have is the date/time changing every time the PDF is opened. The goal is to use this PDF as a template that will be saved as a new copy each time it is opened. I need the date and time to be locked/frozen so when the file is reopened after saving it maintains the unique time stamp.

[try67]

Change the second line to:

if (this.getField("UniqueNumber").valueAsString=="")

this.getField("UniqueNumber").value = util.printd("yymmddHHMM", d);

[DaveMartz2]

Thank you, that resolved my issue. I appreciate your help!