Wiki: Equitable Stroke Control (ESC) is the downward adjustment of individual hole scores for handicap index purposes in order to make handicaps more representative of a player's potential ability. ESC sets a maximum number that a player can post on any hole depending on the player's Course Handicap.
What that says essentially is that it is a system designed to prevent "blow up holes" and save "disaster rounds" from happening.
ESC is used only when a player's actual or most likely score exceeds the player's maximum number based on the table below.
|Course Handicap||Maximum per Hole Score|
|9 or less||Double Bogey|
|10 to 19||7|
|20 to 29||8|
|30 to 39||9|
|40 or more||10|