.. TotalDepth API reference.

Glossary
==========================

.. glossary::
	:sorted:

	LIS
	LIS-79
		Log Information Standard. The original file format used by Schlumberger from 1979 onwards.
		It is a *proprietary*, *de-facto* standard.
	
	LIS-A
		*Enhanced* Log Information Standard. This adds somewhat to the [:term:`LIS-79`] standard.
	
	RP66
		*Recomended Practice 66* is an API standard that describes a more advanced file format for, among other things, wireline logs. Comes in two flavours version 1 and version 2. Often (and incorrectly) referred to as :term:`DLIS`.
		
	DLIS
		This adds schema specific semantics to :term:`RP66`.

	Representation Code
	RepCode
		A code, usually an integer, that describes how a particular run of bytes should be interpreted as a
		value (number, string etc.). For example in the LIS standard representation code 68 describes a 32 bit
		floating point format.
	
	Mnem
	Mnemonic
		[:term:`LIS`] A four byte identifier that is human readable e.g. ``RHOB`` for Bulk Density.
		
	Engineering Value
		A numeric value together with its units of measure.
		
	UOM
		*Units of Measure* for engineering values.
				
	EFLR
		*Explicitly Formatted Logical Record*. This is an internally complete, self-describing record.
		
	IFLR
		*Indirectly Formatted Logical Record*. This is a Logical Record whose format is only completely described by another EFLR. The EFLR that describes an IFLR might be identified formally; for example by a specific reference to an EFLR (as in RP66) or informally; by some heuristic (as in LIS) such as "the immediately prior Logical Record that is type 64".

	DFSR
		[:term:`LIS`] Data Format Specification Record; an EFLR that describes type 0 or type 1 binary IFLRs containing log data. A DFSR consists of a set of Entry Blocks followed by a list of Datum Specification Blocks.
		
		NOTE: The LIS specification associates a particular DFSR type ``0 | 1`` with binary IFLRs of type ``0 | 1``. These collections will be independent of each other and thus permits the simultaneous recording of entirely different data sets. In practice however this rarely happens and it is debatable whether any or all LIS processing implementations support this.
		
	Entry Block
		[:term:`LIS`] A variable length block of data that describes a static value in DFSR. This value is local to a Log Pass. For example and Entry Block might describe the NULL or absent value for any channel in a Log Pass.
		
	Datum Specification Block
	DSB
		[:term:`LIS`] A fixed format data block that defines the characteristics of a single recorded channel in a DFSR.
		
	Log Pass
		A continuos run of data together with any formatting records required to interpret it. "Main Log", "Repeat Section" etc. are seperate examples of Log Pass(es).
		In [:term:`LIS`] a Log Pass is defined by a :term:`DFSR` and zero or more type ``0| 1`` Logical Records.

	Frame Set
		A set of frames representing multi-channel data that is typically depth or time series based.
		
	Xaxis
	X Axis
		The index channel in an array, for example an array of frames. Typically 'depth', 'time' etc.
		
	Physical Record
		[:term:`LIS`] A formal record in a LIS file. Physical Records consist of a header, optional payload and optional trailer. Logical Records consist of the payloads of one or more Physical Records.
		
	Logical Record
		[:term:`LIS`] A formal record from a LIS file. Logical Records consist of a header and optional payload. The Logical Records *type* is identified in the header. The interpretation of the payload of (some) Logical Records types is defined in the LIS standard. Logical Records consist of the payloads of one or more Physical Records. Logical Records are either EFLR or IFLR records.
	
	LRH
	Logical Record header
		The bytes that describe the type and attributes of a Logical Record.