Why do some CAS Registry Number® Identifiers Have Asterisks? Why do some CAS Registry Number® Identifiers Have Asterisks? SM CAS REGISTRY contains more than 77 million unique organic and inorganic chemical substances, such as alloys, coordination compounds, minerals, mixtures, polymers and salts, and more than 65 million sequences. In some CAS REGISTRY records, the CAS Registry Number includes an asterisk and the following note: *Use of this CAS Registry Number alone as a search term in other STN files may result in incomplete search results. These CAS Registry Numbers are included for substances with unknown or variable composition, complex mixtures, or biological substances which do not meet the criteria for CA indexing. The locator code (LC) and the source of registration (SR) fields can provide additional information on their registration. Type “HELP RN*” on STN for more details. All of CAS Registry Numbers with an asterisk have a class identifier (CI) of either CTS (Concept Type Substances) or GRS (Generically Registered Substances). CTS substances are not registered as specific substances, but as concepts. They were assigned a CAS Registry Number for a special registration purpose. Many of these substances were registered for the ® regulatory database, CHEMLIST , which includes information on substances (which are not always fully defined) in national or regional regulatory inventories. An example of a CTS substance is shown in Figure 1. This substance has records in CASM/CAplusSM, Biosis®, EmbaseTM, etc. Since this record has the phrase “structure diagram is not available”, this substance will not be retrieved with a structure search. Figure 1: An example of a substance with CTS as a class identifier. L18 ANSWER 100 OF 306 REGISTRY COPYRIGHT 2013 ACS on STN RN 72060-35-6 REGISTRY * * Use of this CAS Registry Number alone as a search term in other STN files may result in incomplete search results. For additional information, enter HELP RN* at an online arrow prompt (=>). ED Entered STN: 16 Nov 1984 CN Proteins, specific or class, histidine-transporting (CA INDEX NAME) OTHER CA INDEX NAMES: CN Amino acid transporters, histidine transporter CN Transport proteins, histidine transporter CN Transport proteins, histidine-transporting OTHER NAMES: CN Histidine carriers CN Histidine permease CN Histidine transporter CN Histidine transporter protein CN Histidine transporters CN Histidine-transporting proteins CN L-Histidine permease CN Permease, histidine MF Unspecified CI MAN, CTS LC STN Files: BIOSIS, BIOTECHNO, CA, CAPLUS, EMBASE, MEDLINE, TOXCENTER *** STRUCTURE DIAGRAM IS NOT AVAILABLE *** 2 GRS substances can be generic derivatives of specific substances that have been assigned a CAS Registry Number. These CAS Registry Numbers are not used in routine CAS indexing. Similar to the CTS substances, many of these substances were registered for CHEMLIST. An example of a GRS substance ® ® is shown in Figure 2. This substance is a polymer plus it has a record in CHEMCATS , CHEMLIST , SM CA/CAplus and TOXCENTER . It is not completely defined since it is not completely determined where the butyl group resides. Figure 2: An example of a substance with GRS as a class identifier. L5 ANSWER 20000 OF 20323 REGISTRY COPYRIGHT 2013 ACS on STN RN 68002-25-5 REGISTRY * * Use of this CAS Registry Number alone as a search term in other STN files may result in incomplete search results. For additional information, enter HELP RN* at an online arrow prompt (=>). ED Entered STN: 16 Nov 1984 CN 1,3,5-Triazine-2,4,6-triamine, polymer with formaldehyde, butylated (CA INDEX NAME) OTHER CA INDEX NAMES: CN 1,3,5-Triazine-2,4,6-triamine, polymer with formaldehyde, butyl ether DR 59588-08-8, 68037-27-4, 68511-73-9 MF (C3 H6 N6 . C H2 O)x AF Unspecified CI PMS, MAN, GRS PCT Manual registration LC STN Files: CA, CAPLUS, CHEMCATS, CHEMLIST, TOXCENTER Other Sources: DSL**, TSCA** (**Enter CHEMLIST File for up-to-date regulatory information) THE COMPLETE SUBSTANCE MAY NOT BE REPRESENTED BY THESE COMPONENTS. THE CN OR IN FIELD FOR THE COMPLETE SUBSTANCE DESCRIPTION. CM 1 CRN CMF 108-78-1 C3 H6 N6 NH2 N N H2 N H2C N NH2 CM 2 CRN CMF 50-00-0 C H2 O O To get a better understanding of these two categories of compounds (CTS/CI OR GRS/CI), these substances have these attributes: 3 CHECK - 72% from CHEMLIST (CHEMLIST/LC) - 44% with CA as the source of registration or locator code (CA?/LC,SR) 1 - 35% with CAS Client Services as the source of registration (CAS Client Services/SR ) - 34% are polymers (PMS/CI) - 4% from the CHEMCATS database (CHEMCATS/LC) These categories cover 99% of the CTS/GRS substances. Please note that these are not mutually exclusive categories. In summary, where you come across a CAS Registry Number with an asterisk, searching only on its CAS Registry Number in the bibliographic databases will not result in a comprehensive search. It is recommended to supplement the CAS Registry Number search with a name, synonym, description, and trade name (if available) search. Many of these non-specific substances were registered in CAS Registry for CHEMLIST, CAS’s database of regulatory information. For comprehensive searching for these substances with asterisks for references, it is recommended that they are searched by a combination of its CAS Registry Number, possible names or descriptions of the substances, plus any associated trade names. Note 1: CAS Client Services registers new substances upon request. Please see the following URL for more details. http://www.cas.org/products/other-cas-products/client-services . 4