Appendix IV: Entity table

This section compiles the entities (key-value pairs) described throughout this specification, and establishes a common order within a filename. For example, if a file has an acquisition and reconstruction label, the acquisition entity must precede the reconstruction entity. REQUIRED and OPTIONAL entities for a given file type are denoted. Entity formats indicate whether the value is alphanumeric (<label>) or numeric (<index>).

Entity	Format	anat (T1w T2w T1rho T1map T2map T2star FLAIR FLASH PD PDmap PDT2 inplaneT1 inplaneT2 angio)	anat (defacemask)	func (bold sbref events)	func (physio stim)	dwi (dwi bvec bval)	fmap (phasediff phase1 phase2 magnitude1 magnitude2 magnitude fieldmap)	fmap (epi)	beh (events stim physio)	meg (meg channels)	meg (photo coordsystem headshape)
Subject	sub-<label>	REQUIRED	REQUIRED	REQUIRED	REQUIRED	REQUIRED	REQUIRED	REQUIRED	REQUIRED	REQUIRED	REQUIRED
Session	ses-<label>	OPTIONAL	OPTIONAL	OPTIONAL	OPTIONAL	OPTIONAL	OPTIONAL	OPTIONAL	OPTIONAL	OPTIONAL	OPTIONAL
Task	task-<label>			REQUIRED	REQUIRED				REQUIRED	REQUIRED	REQUIRED
Acquisition	acq-<label>	OPTIONAL	OPTIONAL	OPTIONAL	OPTIONAL	OPTIONAL	OPTIONAL	OPTIONAL		OPTIONAL	OPTIONAL
Contrast Enhancing Agent	ce-<label>	OPTIONAL	OPTIONAL	OPTIONAL				OPTIONAL
Reconstruction	rec-<label>	OPTIONAL	OPTIONAL	OPTIONAL	OPTIONAL
Phase-Encoding Direction	dir-<label>			OPTIONAL		OPTIONAL		REQUIRED
Run	run-<index>			OPTIONAL	OPTIONAL	OPTIONAL	OPTIONAL	OPTIONAL		OPTIONAL	OPTIONAL
Corresponding modality	mod-<label>		OPTIONAL
Echo	echo-<index>			OPTIONAL
Recording	recording-<label>				OPTIONAL
Processed (on device)	proc-<label>				OPTIONAL					OPTIONAL	OPTIONAL