OB marker

An OB marker, short for "out of bounds marker", is used in Singapore to denote what topics are permissible for public discussion. The full form of the word is rarely used.

The term is adopted from golf, where an out of bounds marker denotes the area beyond which playing is not allowed. However, unlike golf, the OB markers of Singaporean political discourse are not visible. The term "OB markers" was first used in 1991 by the then-Minister for Information and the Arts George Yeo to describe the boundaries of acceptable political discourse.