A physical package is replaceable if it is possible to replace (FRU or upgrade) the element with a physically different one. ...

A physical package is replaceable  if it is possible to replace (FRU or upgrade) the element with a physically different one.  For example, some computer systems allow the main processor chip to be upgraded to one of a higher clock rating. In this case, the processor is said to be replaceable . Another example is a power supply package mounted on sliding rails. All removable packages are inherently replaceable .