From IFWiki

Northeast (or north-east) is a direction. It is one of the four diagonal directions, and one of the eight compass directions. Its opposite direction is southwest.

Northeast is associated with the top right corner of a map; most maps are meant to be read with the north-end up. If you are facing north, then northeast is in a diagonal direction both forward and to your right.

Some early IF games do not support diagonal directions like northeast. In ADRIFT Generator 4.00, diagonal directions are initially disabled and must be explicitly enabled by an ADRIFT author before they can be used in a game.

The NORTHEAST command

Typing NORTHEAST means GO NORTHEAST or WALK NORTHEAST. That is, direct the player character northeastward from their current location. Assuming there's an exit in that direction and nothing is blocking or hindering the character, the PC will travel northeast to an adjacent location.

NORTHEAST is such a common enough command that it has an abbreviation: NE.

Northeast in other languages

Some languages and regions prefer to hyphenate the names of diagonal directions. Some language library extensions support both spellings; others don't. Only the unhyphenated variants are listed here.

Dutch noordoost no
English northeast ne
Esperanto nordorienten no, nor1
French nordest ne
German Nordosten no
Italian nordest ne
Spanish nordeste ne
Swedish nordost no

1 Esperanto's words for northwest and northeast are nordokcidento and nordoriento, which means it's problematic to use no as an abbreviation for either of them. And ne is the Esperanto word for "no" and "not", so that's not an option. There aren't enough Esperanto IF games to see any clear concensus on how to abbreviate nordorienten, but no and nor seem the most likely possibilities.

Code Compare

Directions like NORTHEAST tend to be implemented both as room properties and as objects in their own right. The NORTHEAST command, however, tends to be parsed or reinterpreted as a GO command acting on the northeast object.

Code Compare: Northeast
ADRIFT 4:Move NorthEast to Field begin.pngPantryField end.png
Inform 6:The ne_to property and ne_obj object
Inform 7:The northeast direction
TADS 3:The northeast link property and northeastDirection object