ANSI INCITS 540:2018 pdf free download – Fibre Channel – Non-Volatile Memory Express (FC-NVMe)
3.4.1 ignored: A keyword used to describe an unused bit, byte, word, field or code value. The contents or value of an ignored bit, byte, word, field or code value shall not be examined by the receiving device and may be set to any value by the transmitting device.
3.4.2 invalid: A keyword used to describe an illegal or unsupported bit, byte, word, field or code value. Receipt of an invalid bit, byte, word, field or code value shall be reported as an error.
3.4.3 mandatory: A keyword indicating an item that is required to be implemented as defined in this standard.
3.4.4 may: A keyword that indicates flexibility of choice with no implied preference (equivalent to “may or may not”).
3.4.5 may not: A keyword that indicates flexibility of choice with no implied preference (equivalent to “may or may not”).
3.4.6 optional: A keyword that describes features that are not required to be implemented by this standard. However, if any optional feature defined by this standard is implemented, then it shall be implemented as defined in this standard.
3.4.7 reserved: A keyword referring to bits, bytes, words, fields and code values that are set aside for future standardization. A reserved bit, byte, word or field shall be set to zero, or in accordance with a future extension to this standard. Recipients should not check reserved bits, bytes, words or fields for zero values. Receipt of reserved code values in defined fields shall be reported as an error.
3.4.8 shall: A keyword indicating a mandatory requirement. Designers are required to implement all such mandatory requirements to ensure interoperability with other products that conform to this standard.
3.4.9 should: A keyword indicating flexibility of choice with a strongly preferred alternative;equivalent to the phrase “it is strongly recommended”.
3.4.10 x or xx: The value of the bit or field is not relevant.
3.5 Editorial conventions
In FC-NVMe, a number of conditions, mechanisms, sequences, parameters, events, states, or similar terms are printed with the first letter of each word in uppercase and the rest lowercase (e.g., Exchange, Sequence). Any lowercase uses of these words have the normal technical English meanings. Lists sequenced by letters (e.g., a-red, b-blue, c-green) show no ordering relationship between the listed items. Numbered lists (e.g., 1 -red, 2-blue, 3-green) show an ordering relationship between the listed items. In case of any conflict between figure, table, and text, the text, then tables, and finally figures take precedence. Exceptions to this convention are indicated in the appropriate clauses. In all of the figures, tables, and text of this document, the most significant bit of a binary quantity is shown on the left side. Exceptions to this convention are indicated in the appropriate clauses. Data structures in this standard are displayed in Fibre Channel format (i.e., “big-endian”), while specifications originating in NVMe over Fabrics display data structures in Ethernet format (i.e., “little- endian”). If the value of the bit or field is not relevant, then x or xx appears in place of a specific value. If a field or a control bit in a frame is specified as not meaningful, then the entity that receives the frame shall not check that field or control bit. Numbers that are not immediately followed by lower-case b or h are decimal values. Numbers immediately followed by lower-case b (xxb) are binary values.