I would like to revise my statement of purpose/resume/writing sample/supplementary application/uploaded transcripts after submitting my application. Is this permitted?

Until submitting your application, you can update your application as often as you wish. Once you have submitted your application, it is immediately sent to the program/department for review. It is therefore not possible for the Graduate School to update any supporting documentation following the submission of the application. If you wish to discuss the possibility of updating documentation following submission, this is up to the discretion and the processing of the academic department.