Deleted Registry Number

In addition to the current Registry Number the Deleted Registry Numbers are also transmitted. They should not be left aside in the query because the citations are not changed retroactively (Sect. 4.1). During a single search, 30,000 Registry Numbers may be transferred fi om the Registry File on to the CA File. 

Both common and systematic names of compounds are used throughout this volume, depending on which the Editor-in-Chief felt was more appropriate. Preparations appear in alphabetical order of titles of the synthetic procedures. The Chemical Abstracts indexing name for each title compound, if it differs from the title name, is given as a subtitle. Systematic Chemical Abstracts nomenclature, used in both the 8th and 9th Collective Indexes for the title compound and a selection of other compounds mentioned in the procedure, is provided in an appendix at the end of each preparation. Registry numbers, which are useful in computer searching and identification, are also provided in these appendixes. Whenever two names are concurrently in use and one name is the correct Chemical Abstracts name, that name is adopted. For example, both diethyl ether and ethyl ether are normally used. Since ethyl ether is the established Chemical Abstracts name for the 8th Collective Index, it has been used in this volume. The 9th Collective Index name is 1, l -oxybisethane, which the Editors consider too cumbersome. The prefix -is deleted from M-alkanes and n-alkyls. All reported dimensions are now expressed in Systeme International units. 

IDE all dictionary fields except ring data, up to 50 chemical names REG Registry Number, Deleted RN, Replacing RN, Preferred RN, Alternate RN SCAN CA Index Name, length of sequence (in biosequences), molecular formulae, substance class, structure (in random order of documents)... 

A CASRN is a numeric identifier that can contain up to ten digits, divided by hyphens into three parts. The last digit is a check digit by which the validity and uniqueness of the entire number is verified by computer. Elimination of the last number allows estimation of the total number of assigned CASRN. Because numbers have been deleted from the Registry, the current total of CASRN assigned is about 100 million based on the most recent CASRN assigned. 

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