Notes. 1  For many of the articles on the NIDA Web site, such as the ones found in the DrugFacts section, no author is necessary. You may leave this out of your citation as in the example below if no author is given. 2  The date of posting/revision can be found at the top and/or bottom of the page in the footer.
HKEY_CLASSES_ROOT. HKEY_CLASSES_ROOT or HKCR is an alias (i.e. a reference) to HKEY_LOCAL_MACHINE\Software\Classes. A separate root key is added mainly so software developers have direct access to this data without dipping in to HKLM. HKCR contains data related to applications, shortcuts, and file extension associations.
In the relational model of databases, a candidate key of a relation is a minimal superkey for that relation; that is, a set of attributes such that:onversely, an attribute that does not occur in ANY candidate key is called a non-prime attribute. Since a relation contains no duplicate tuples, the set of all its attributes is a superkey if NULL values are not used. It follows that every relation will have at least one candidate key.