There are numerous different kinds of doors on Sindome. Simple key based doors are relatively uncommon. Most doors are keypad or retinal scanning doors.
Some doors have a keypad on only one side, such as CUBE HOTELS. These doors may lock automatically when closed. This will typically be indicated by the entry light going red.
Some doors, like apartments, may not lock automatically and instead you will need to type 'lock '.
To unlock an apartment or cube door, you can type 'push open on ' which will UNLOCK the door. This is usually symbolized with the entry light going green. This just means the door is unlocked. It can be opened from either the inside, or the outside at this point.
To open a closed but unlocked door you use 'open '.
Be wary, some apartment doors can be upgraded so that they require the entry combo to get in OR to get out.
There are specific help files available for certain types of doors. For example if it is a combo lock door (one where you put the code in) you can type 'help doorname' where doorname is the FULL EXIT NAME of the door. This means doing 'help o' will not work, but doing 'help out' might.
help hallway help east
Using the alias like 'help h' will not work.
For retinal scanner exits, you can 'verify me for '.
Please review the help files associated with the specific door.