e/Frame fields in general relativity

Information
has gloss	eng: In general relativity, a frame field (also called a tetrad or vierbein) is an orthonormal set of four vector fields, one timelike and three spacelike, defined on a Lorentzian manifold that is physically interpreted as a model of spacetime. The timelike unit vector field is often denoted by \vece}_0 and the three spacelike unit vector fields by \vece}_1, \vece}_2, \, \vece}_3. All tensorial quantities defined on the manifold can be expressed using the frame field and its dual coframe field.
lexicalization	eng: Frame fields in general relativity
instance of	(noun) a system of assumptions and standards that sanction behavior and give it meaning frame of reference, frame

Meaning
Castilian
has gloss	spa: En física, un observador es cualquier ente capaz de realizar mediciones de magnitudes físicas de un sistema físico para obtener información sobre el estado físico de dicho sistema.
lexicalization	spa: observador