Modifies a noun

• protection: There should be a requirement for the front underrun protection system to be energy absorbing.

• error: However, sometimes you may need to burn at a lower speed in order to avoid a buffer underrun error.

• device: The fitting of a rear underrun device on trucks is obligatory nowadays.

Noun used with modifier

• buffer: However, sometimes you may need to burn at a lower speed in order to avoid a buffer underrun error.