ISO/IEC 14776-253:2023 情報技術 — Small Computer System Interface (SCSI) — Part 253: USB 接続 SCSI - 3 (UAS-3) | ページ 6

3 Definitions, symbols, abbreviations, and conventions

3.1 Definitions

3.2 Symbols and abbreviations

3.2.1 Abbreviations

Abbreviations used in this standard:

3.2.2 Units

Units used in this standard:

3.2.3 Mathematical operators

Mathematical operators used in this standard:

3.3 Keywords

3.3.1 invalid

keyword used to describe an illegal or unsupported bit, byte, word, field or code value

3.3.2 mandatory

keyword indicating an item that is required to be implemented as defined in this standard

3.3.3 may

keyword that indicates flexibility of choice with no implied preference

3.3.4 may not

keyword that indicates flexibility of choice with no implied preference

3.3.5 obsolete

keyword indicating that an item was defined in prior SCSI standards but has been removed from this standard

3.3.6 option, optional

keywords that describe features that are not required to be implemented by this standard

3.3.7 reserved

keyword referring to bits, bytes, words, fields, and code values that are set aside for future standardization

3.3.8 shall

keyword indicating a mandatory requirement

3.3.9 should

keyword indicating flexibility of choice with a strongly preferred alternative

3.3.10 vendor specific

something (e.g., a bit, field, code value) that is not defined by this standard

3.4 Editorial conventions

Certain words and terms used in this standard have a specific meaning beyond the normal English meaning. These words and terms are defined either in 3.1 or in the text where they first appear.

Upper case is used when referring to the name of a numeric value defined in this specification or a formal attribute possessed by an entity. When necessary for clarity, names of objects, procedure calls, arguments or discrete states are capitalized or set in bold type. Names of fields are identified using small capital letters (e.g., naca bit).

Names of procedure calls are identified by a name in bold type (e.g., Execute Command ). Names of arguments are denoted by capitalizing each word in the name (e.g., Sense Data is the name of an argument in the Execute Command procedure call).

Quantities having a defined numeric value are identified by large capital letters (e.g., CHECK CONDITION). Quantities having a discrete but unspecified value are identified using small capital letters. (e.g., task complete, indicates a quantity returned by the Execute Command procedure call). Such quantities are associated with an event or indication whose observable behavior or value is specific to a given implementation standard.

Lists sequenced by letters (e.g., a-red, b-blue, c-green) show no priority relationship between the listed items. Numbered lists (e.g., 1-red, 2-blue, 3-green) show a priority ordering between the listed items.

If a conflict arises between text, tables, or figures, the order of precedence to resolve the conflicts is text; then tables; and finally figures. Not all tables or figures are fully described in the text. Tables show data format and values.

Notes and examples do not constitute any requirements for implementors.

3.5 Numeric and character conventions

3.5.1 Numeric conventions

A binary number is represented in this standard by any sequence of digits comprised of only the Arabic numerals 0 and 1 immediately followed by a lower-case b (e.g., 0101b). Underscores or spaces may be included in binary number representations to increase readability or delineate field boundaries (e.g., 0 0101 1010b or 0_0101_1010b).

A hexadecimal number is represented in this standard by any sequence of digits comprised of only the Arabic numerals 0 through 9 and/or the upper-case English letters A through F immediately followed by a lower-case h (e.g., FA23h). Underscores or spaces may be included in hexadecimal number representations to increase readability or delineate field boundaries (e.g., B FD8C FA23h or B_FD8C_FA23h).

A decimal number is represented in this standard by any sequence of digits comprised of only the Arabic numerals 0 through 9 not immediately followed by a lower-case b or lower-case h (e.g., 25).

This standard uses the following conventions for representing decimal numbers:

• a) the decimal separator (i.e., separating the integer and fractional portions of the number) is a period;
• b) the thousands separator (i.e., separating groups of three digits in a portion of the number) is a space; and
• c) the thousands separator is used in both the integer portion and the fraction portion of a number.

Table 1 shows some examples of decimal numbers using various numbering conventions.

3.5.2 Byte encoded character strings conventions

When this standard requires one or more bytes to contain specific encoded characters, the specific characters are enclosed in single quotation marks. The single quotation marks identify the start and end of the characters that are required to be encoded but are not themselves to be encoded. The characters that are to be encoded are shown in the case that is to be encoded.

An ASCII space character (i.e., 20h) may be represented in a string by the character ‘¬’ (e.g., ‘SCSI¬device’).

The encoded characters and the single quotation marks that enclose them are preceded by text that specifies the character encoding methodology and the number of characters required to be encoded.

3.6 Sequence figure notation

A sequence figure describes sequences of communication between a requestor and a responder. Figure 1 is an example sequence figure. A line with an arrowhead that points to the responder represents a communication from the requestor to the responder. A line with an arrowhead that points to the requestor represents a communication from the responder to the requestor.

Each line with an arrowhead has a label. The label describes the communication between the requestor and the responder.

Communications that appear near the top of a sequence figure occur earlier in time than communications that appear below them.

3.7 Notation for procedures and functions

In this standard, the model for functional interfaces between objects is the callable procedure. Such interfaces are specified using the following notation:

• [Result =] Procedure Name (IN ([input-1] [,input-2] ...), OUT ([output-1] [,output-2] ...))

Where:

Result:A single value representing the outcome of the procedure or function.

Procedure Name:descriptive name for the function to be performed.

IN (Input-1, Input-2, ...)A comma-separated list of names identifying caller-supplied input data objects.

OUT (Output-1, Output-2, ...)A comma-separated list of names identifying output data objects to be returned by the procedure.

[...] Brackets enclose optional or conditional parameters and arguments.

This notation allows data objects to be specified as inputs and outputs.

In this standard, the notation Procedure Name () is used to indicate the name of a procedure without specifying the input data objects or output data objects.