Order Management Extensions : Disable modification on some fields

Summary

After the sales order gets submitted we would like to add restrictions on modifying certain fields by the end user

Content

Hello,

The customer wants to allow modification of certain sales orders fields, between the creation of the sales order and before it becomes "interfaced". All other fields will have to remain unchanged.

1) How can we access current and "stored" sales orders through the Groovy extension ?

2) Is there a way we can flag modifications made by the user on the fly ?

Thank you for your ideas / help suggestions.

NB : we have already checked FA: SCM: OM: How To: Defining Order Management Extensions - Including Code Snippets (Doc ID 2428750.1) and did not find an answer.