# 1.4 Typographic conventions

This document uses the typographic and illustrative conventions described below:
 Typographic Convention Typographic convention description Plain text The normal text typeface is used for the vast majority of the descriptive text in a specification. Any plain text that is underlined and in blue indicates an active link to the crossreference. Click on the word to follow the hyperlink. Bold In text, a Bold typeface identifies a processor register name. In other instances, a Bold typeface can be used as a running head within a paragraph. Italic In text, an Italic typeface can be used as emphasis to introduce a new term or to indicate a manual or specification name. `BOLD Monospace` Computer code, example code segments, and all prototype code segments use a `BOLD Monospace` typeface with a dark red color. These code listings normally appear in one or more separate paragraphs, though words or segments can also be embedded in a normal text paragraph. Words in a `Bold Monospace` typeface that is underlined and in blue indicate an active hyper link to the code definition for that function or type definition. Click on the word to follow the hyper link. `\$(VAR)` This symbol VAR defined by the utility or input files. Italic Bold In code or in text, words in Italic Bold indicate placeholder names for variable information that must be supplied (i.e., arguments).
Note: Due to management and file size considerations, only the first occurrence of the reference on each page is an active link. Subsequent references on the same page will not be actively linked to the definition and will use the standard, non-underlined BOLD Monospace typeface. Find the first instance of the name (in the underlined BOLD Monospace typeface) on the page and click on the word to jump to the function or type definition.
The following typographic conventions are used in this document to illustrate the Extended Backus-Naur Form.
 [item] Square brackets denote the enclosed item is optional. `{item}` Curly braces denote a choice or selection item, only one of which may occur on a given line. `` Angle brackets denote a name for an item. `(range-range)` Parenthesis with characters and dash characters denote ranges of values, for example, (a-zA-Z0-9) indicates a single alphanumeric character, while (0-9) indicates a single digit. "item" Characters within quotation marks are the exact content of an item, as they must appear in the output text file. `?` The question mark denotes zero or one occurrences of an item. `*` The star character denotes zero or more occurrences of an item. `+` The plus character denotes one or more occurrences of an item. `item{n}` A superscript number, n, is the number occurrences of the item that must be used. Example: (0-9)8 indicates that there must be exactly eight digits, so 01234567 is valid, while 1234567 is not valid. `item{n,}` A superscript number, n, within curly braces followed by a comma "," indicates the minimum number of occurrences of the item, with no maximum number of occurrences. `item{,n}` A superscript number, n, within curly brackets, preceded by a comma ","indicates a maximum number of occurrences of the item. `item{n,m}` A super script number, n, followed by a comma "," and a number, m, indicates that the number of occurrences can be from n to m occurrences of the item, inclusive.