4. Subject to section 6, where all or part of the explicit chemical name of a substance can be described with a structural diagram, any of the following is a single distinctive element of that name or part:

• (a) a locant;

• (b) a locant and multiplicative prefix that together specify the position and number of a chemical group;

• (c) the name of a chemical group;

• (d) the name of the parent structure and the locant of a chemical group bonded to the parent structure; or

• (e) in the case of a salt, the name and multiplicative prefix of a single cation or anion of the salt.

• 5. (1) Subject to subsection (2) and section 6, where the explicit chemical name of a substance cannot be described with a structural diagram, either of the following is a single distinctive element of that name:

  • (a) a constituent of the name that describes a complex mixture of a known class of chemicals including any substance that is recorded in the Chemical Abstracts Chemical Substance Index as an indefinite or general derivative of a specific chemical substance; or

  • (b) a constituent of the name that describes a complex mixture of an unknown class of chemicals including a substance that is recorded or is capable of being recorded in the Chemical Abstracts General Subject Index and can be named only by using descriptive or illustrative terms.

• (2) For the purposes of subsection (1), where a part of the explicit chemical name can be described with a structural diagram, the masking of that part shall be carried out in accordance with section 4.

6. Where a substance referred to in section 4 or 5 contains a chemical group that includes a carbon atom possessing more than a single valence, the name of the chemical group shall not be masked where the carbon atom is

• (a) attached directly to an acyclic carbon atom; or

• (b) included within a ring system.

7. The name of a parent structure of a substance referred to in section 4 or 5 may be masked only by one of the following non-descriptive terms, as appropriate:

• (a) alkyl or alkane;

• (b) alkenyl or alkene;

• (c) alkynyl or alkyne;

• (d) carbomonocyclic or carbomonocycle;

• (e) carbopolycyclic or carbopolycycle;

• (f) heteromonocyclic or heteromonocycle; or

• (g) heteropolycyclic or heteropolycycle.

8. Where all or any part of the name of a substance is an explicit biological name, any of the following is a single distinctive element of that explicit biological name:

• (a) the genus name;

• (b) the species name;

• (c) the strain name;

• (d) the common biological name;

• (e) the source;

• (f) the culture history;

• (g) the phenotypic or genotypic characteristics;

• (h) the use; or

• (i) any other pertinent descriptive information.