Depth scale name	Acronym	Datum	Description	Previous unit	Type depth
Drillers depth scales	Drilling depth below rig floor	DRF	Rig floor	The sum of lengths of all drill string components deployed beneath the rig floor. Includes length of all components and the portions thereof below rig floor.	mbrf	Measured
	Drilling depth below seafloor	DSF	Seafloor	The length of all drill string components between seafloor and target.	mbsf	Processed
LWD and MWD depth scales	LWD depth below rig floor	LRF	Rig floor	The sum of lengths of all drill string components deployed beneath the rig floor reference.	mbrf	Measured
	LWD depth below seafloor	LSF	Seafloor	The length of all drill string components between seafloor and target.	mbsf	Processed
Mud depth scales	Mud depth below rig floor	MRF	Rig floor	The length of all drill string components between where cuttings and gas originate and the rig floor based on lag time of arrival at rig floor and mud pump rate.	NA	Processed
	Mud depth below seafloor	MSF	Seafloor	MRF with seafloor depth below rig floor subtracted.	NA	Processed
Core depth scales	Core depth below seafloor	CSF-A	Seafloor	Distance from seafloor to target within recovered core. Combines DSF to top of cored interval with curated section length to target within cored material. This method allows overlap at cored interval and section boundaries.	mbsf	Processed
	Core depth below seafloor	CSF-B	Seafloor	Distance from seafloor to target within recovered core. Combines DSF to top of cored interval with curated length to target within cored material. This method applies compression algorithm (i.e., scaling) if recovery is >100%.		Processed
Composite depth scales	Core composite depth below seafloor	CCSF	Seafloor	Distance from seafloor to target within recovered core using a scale of adjusted depths constructed to resolve gaps in the core recovery and depth inconsistencies.	mcd	Composite
Seismic depth scales	Seismic depth below seafloor	SSF	Seafloor	Distance below seafloor and target derived from seismic traveltime, velocity, and water depth.	m	Processed
	Seismic depth below sea level	SSL	Sea level	Distance below sea level derived from seismic traveltime and velocity.	m	Processed

LWD = logging while drilling, MWD = measurement while drilling. NA = not applicable. See IODP Depth Scale Terminology at www.iodp.org/program-policies/procedures/guidelines/.

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