GM: y

From GMpedia.org Wiki

y
Type:	variable
Globalism:	Local
Editable:	Yes

The y variable is a local variable that represents the y position of an object in a room.

There is an x-axis and an y-axis on the image. The number on the y-axis indicates where the object is relative to the point (0,0) in vertical direction.

The gray area indicates the upper left corner of a room in Game Maker. When editing a room, the white areas are never visible.