Glossary

Datum Specification Block
DSB

[LIS] A fixed format data block that defines the characteristics of a single recorded channel in a DFSR.

DFSR

[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.

DLIS

This adds schema specific semantics to RP66.

EFLR

Explicitly Formatted Logical Record. This is an internally complete, self-describing record.

Engineering Value

A numeric value together with its units of measure.

Entry Block

[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.

Frame Set

A set of frames representing multi-channel data that is typically depth or time series based.

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”.

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 [LIS-79] standard.

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 [LIS] a Log Pass is defined by a DFSR and zero or more type 0| 1 Logical Records.

Logical Record

[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.

Mnem
Mnemonic

[LIS] A four byte identifier that is human readable e.g. RHOB for Bulk Density.

Physical Record

[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.

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.

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 DLIS.

UOM

Units of Measure for engineering values.

Xaxis
X Axis

The index channel in an array, for example an array of frames. Typically ‘depth’, ‘time’ etc.