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Conventions

ABNF Grammar and extensions are used in DICOM part PS3.18 to describe the syntax of the request and response messages for transactions.

Message Syntax

'%s' prefix for denoting case sensitive strings.
Syntactic variables are lowercase.
Terminal rules are uppercase. For example, 'SP' stands for the US-ASCII space (0x20) literal character, and 'CRLF' stands for the ASCII carriage return (0xD) and line feed (0xA) literal characters.
Header Field names are capitalized and quotation marks that denote literal strings for header field names are omitted. The Header Field names are the only capitalized names used in the grammar.
Resources are identified by URIs. Each service defines the resources it manages, and the URI Templates used to define the structure of the URIs that reference them.
URI Templates - extended to allow case sensitive variable name.
varchar = %x20-21 / %x23-7E / pct-encoded
List Rule ('#') - The ABNF has been extended with the List Rule, which is used to define comma-separated lists. It does not allow empty lists or empty list elements.
The term HTTP refers to the family of HTTP protocols including HTTP/1.1, HTTPS/1.1, HTTP/2, and HTTPS/2.
Common Syntactic Rules for Data Types:

Name	Rule
int	= [+ / -] 1*DIGIT
	; An integer
uint	= 1*DIGIT
	; An unsigned integer
non-zero-digit	= %31-39
pos-int	= non-zero-digit *DIGIT
	; An integer greater than zero
decimal	=int ["." uint] [("E" / "e") int]
	; a fixed- or floating-point number with at most 16 characters
string	= %s 1*QCHAR
	; A case sensitive string
base64	; Use base64 defined in RFC4648 Section 5
uid	= uid-root 1*("." uid-part)
uid-root	= "0" / "1" / "2"
uid-part	= "0" / pos-int