I am wondering if Ext4 file system stores names or IDs for file ownership information? Most probably the IDs... but that makes another question.
Does all Ubuntu versions have standardized IDs for common usernames? For example:
What about other Linux distributions? BSDs?
Edited to clarify: What happens when I mount Ext4 HDD on different Linux where user IDs are different? Are permissions/ownership broken? Or Ext4 stores usernames and groupnames? What happens if particular group or user is deleted?