A little curiosity about PatientID

Looking at the studies parameter of OHIF’s qido.js, it uses the 00100020 tag instead of the PatientID.
In the worklist.tsx, it uses the word mrn.
Since I am a layman in this field, I am curious as to why it is used like this.
The question was written through a translator, so it may be awkward.
I appreciate your understanding.