(metric template allowing metrics to be written as a general expansion)
A Johannsen-Psaltis metric (JP metric) is a metric
applicable to modifications to general relativity (GR). It includes an
expansion term that is general enough that it can be
customized to leave it as "plain GR"
or make it any of many of the proposed modifications.
Thus, it can provide a framework for comparison,
including comparison of theory with observation.
A spacetime with such a metric is termed
a Johannsen-Psaltis spacetime (JP spacetime).