Maximum Screen Objects
The size of the screen object table is set by the Maximum Screen Objects property of the game's OBJECT file. The interpreter allocates memory for the screen object table based on the Maximum Screen Objects value when the game starts. The size of the table cannot be adjusted after that.
This size varies between 15 - 16 usually.
Sources
Some of the content of this page was taken from the AGI Studio & WinAGI help files.