Stephanie byrd is a coder at greensburg medical center. her user id is sbyrd. she recently got married and wants her user id changed to slopez, to reflect her married name. stephanie is told by the office administrator that once a user id is assigned, it cannot be changed. why can't the user id be changed?

ID could be changed, but most software doesn't allow it for complexity and security reasons. What sometimes is possible is to create a new account with a new user ID, migrate the information of the old account to the new one and block the old account.

Explanation:

Security reason: For the sake of maintaining a consistent user identity,  changes are not allowed, imagine what would happen if an user that is on everybody's block list decide to change it's ID, the blocking filers will stop working and this blocked user could damage people again. Complexity reason: To ensure consistency across your system and to avoid security problems usernames can not be unique IDs in a database so you need a more complex system.

Wash your hands often and recycle your trash instead of just throwing it away.