Ordinary identifiers are identifiers not surrounded by double quotation marks. Delimited identifiers are identifiers surrounded by double quotation marks.
An ordinary identifier must begin with a letter and contain only letters,
underscore characters (_), and digits. The permitted letters and digits include
all Unicode letters and digits, but
Periods within delimited identifiers are not separators but are part of the identifier (the name of the dictionary object being represented).
So, in the following example:
is a dictionary object, while
is a dictionary object qualified by another dictionary object (such as a column named "B" within the table "A").