DLIS-RP66-PART-7

Part 7: Basic Schema Dictionary

Edition 1

This part lists and defines a dictionary of reference values for attributes belonging to the basic schema (see Part 6).

Changes to the basic schema dictionary are recommended by the Subcommittee On Recommended Format For Digital Well Data and approved by POSC. Changes may include addition of new terms or removal of obsolete terms. A term removed in one edition may be restored in a later edition only if restored with its previous meaning. A new edition of the basic schema dictionary occurs when approved by POSC, and has an edition number obtained by adding 1 to the previous edition number.

The tables presented here contain the various reference values defined for attributes of the basic schema that have controlled values. There is one table per controlled attribute. Each attribute is identified by its label preceded by the object type to which it belongs and separated by a colon (:). Reference values are listed alphabetically by object type first and by attribute second.

All basic schema reference values use representation code IDENT.

Table 1 - CHANNEL:DIRECTION Reference Values
Reference Value	Description
DECREASING	Channel value strictly decreases as frame number increases.
INCREASING	Channel value strictly increases as frame number increases.
NON-DECREASING	Channel value does not decrease as frame number increases.
NON-INCREASING	Channel value does not increase as frame number increases.

Table 2 - CHANNEL:FLAGS Reference Values
Reference Value	Description
EXPLICIT-SIZE	When present, the channel is explicitly sized. In this case a dimension or aggregate descriptor for the channel will be found at the beginning of each frame block in which the channel value occurs. A dimension or aggregate descriptor consists of a count followed by a standard DIMENSION or AGGREGATE value, all written using representation code ULONG only. The descriptor is recorded at the beginning of the frame block immediately following the last frame num- ber. If more than one channel is explicitly sized, then descriptors are written in the same order as the explicitly- sized channels in the frames. When a channel is explicitly-sized, then DIMENSION and AGGREGATE attributes shall be absent from the CHAN- NEL object. Either DIMENSION-LIMIT or AGGRE- GATE-LIMIT but not both shall be present to indicate the the kind of descriptor and its maximum count for any frame in the frame type. ELEMENT-LIMIT shall be present to indicate the maximum number of elements of the channel's value for any frame in the frame type.

The frame number of any other frame shall be one greater than the frame number of the previous frame.

Table 3 - FRAME:FLAGS Reference Values
Reference Value	Description
ENCRYPTED	IFLRs associated with the frame type are encrypted if and only if this value is present.
INCREASING	When present, frame numbers shall increase in the order in which frames occur, but there may be gaps. The frame num- ber of the first frame may be any positive integer.
SEQUENTIAL	When present, frame numbers shall increase sequentially (no gaps) in the order in which frames are written. The frame number of the first frame may be any positive integer.
UNORDERED	When present, frame numbers may occur in any order. Flag values INCREASING, SEQUENTIAL, and UNORDERED are mutually exclusive. If none are present, then SEQUENTIAL is assumed by default.

There are two reasons for having sequentially-ordered frame numbers. First, it provides an indicator of when records have been lost - a frame number will be observed missing. Second, it allows seeking frames by position without having to count all frames in between.

On the other hand, it can be useful to have unordered frames when using an indexing hypergrid for the frame type (see Part 6). Since location on the hypergrid is a function of frame number, unordered frame numbers allow representation of different kinds of "cuts" through the hypergrid, as well as dropouts and other irregularities.

Table 4 - PROCESS:STATUS Reference Values
Reference Value	Description
ABORTED	The process was aborted.
COMPLETE	The process completed.
IN-PROGRESS	The process began but did not complete.