Formally, a Humdrum representation may be defined as any ASCII input containing zero or more comments, data records or interpretations -- with the restriction that no data records or local comments appear without a prior exclusive interpretation, and that the file maintain a coherent spine organization.

Humdrum comments are records (lines) that begin with an exclamation mark (!). Local comments begin each active spine with a single exclamation mark, whereas gobal comments begin with two exclamation marks (!!) at the beginning of the record.

Humdrum interpretations are records that begin with an asterisk (*). Tandem interpretations begin each active spine with a single asterisk, whereas exclusive interpretations begin the record with one or more asterisks and have at least one active spine beginning with two asterisks. Spine-path indicators are special types of interpretations that include any one of the following tokens: *+ *- *v *^ or *x. Spine-path indicators cannot appear on the same line with a tandem or exclusive interpretation.

Any record that does not begin with either an exclamation mark of asterisk is a data record.

The following table defines some of the pertinent Humdrum terminology.

record	a line of text; a sequences of (zero or more) ASCII characters
	terminated by a carriage return or newline character
data record	any record which is not a comment or an interpretation
comment	a global or local comment
global comment	any record beginning with two exclamation marks (!!)
local comment	any record beginning with a single exclamation mark (!)
interpretation	an exclusive or tandem interpretation, or a spine-path indicator
exclusive interpretation	any record beginning with one or more asterisks (**) and
	having at least one active spine beginning with two asterisks
tandem interpretation	any record in which each active spine begins with a single
	asterisk, excluding spine-path indicators
spine-path indicator	one of the following five interpretations: *+ *- *v *^ *x
null token	the period (.) either alone on a single record or
	separated from other characters by tabs
spine	a column of information -- including data records, local
	comments, and interpretations.

The following files may satisfy the Humdrum syntactical requirements:

• a file containing data records preceded by at least one exclusive interpretation
• a file containing only comments and interpretations
• a file containing only interpretations
• a file containing only global comments
• a totally empty file.

Additional interpretations may be added throughout the file. Global comments may appear anywhere in the file. Local comments and data records can appear only after a spine has been initiated via an exclusive interpretation.

Illegal constructions in Humdrum include the following:

• empty record (i.e. a record containing only a carriage return or newline)
• record containing only tabs
• any record beginning with a tab
• any record ending with a tab (except in a global comment)
• any record containing two successive tab characters (except in a global comment)
• any data record with fewer or more spines than the immediately preceding data or exclusive interpretation record
• spine-path record containing only one join-spine indication
• spine-path record containing only one exchange-spine indication, or containing more than two exchange-spine indicators.

*+	- start a new spine
*-	- terminate a current spine
*^	- split a spine (into two)
*v	- join (two or more) spines into one
*x	- exchange the position of two spines

The use of various spine-path indicators is illustrated below:

1	2	3
*	*+	*
*	*	**inter	*		(must follow immediately after)
1	2	new	3
1	2	3
*	*-	*
1	3
1	2	3
*	*^	*
1	2a	2b	3
1	2	3
*	*v	*v
1	2&3
1	2	3
*x	*x	*
2	1	3
More complex examples:
1	2	3	4	5
*	*-	*	*-	*
*v	*v	*v
1&3&5
1	2	3	4
*	*	*v	*v
*	*x	*x
*v	*v	*
1&3&4	2
1	2	3	4
*v	*v	*^	*^
1&2	3a	3b	4a	4b
1	2	3	4	5
*	*-	*	*	*
*v	*v	*	*
*	*^	*
*	*	*+	*
*	*	*	**inter	*
1&3	4a	4b	new	5

-h	displays a help screen summarizing the command syntax
-v	verbose mode

The -v option invokes the verbose mode which provides summary information and statistics concerning the input file. A list of all of interpretations found in the file is output. In addition, an inventory of all of the ASCII signifiers (characters) found in the data records is output. The total number of data records is also provided, as well as the number of null tokens encountered.

The verbose summary also produces a number of statistics related to the spine-organization in the Humdrum file. Both the minimum and maximum number of spines are identified. The paths of the various spines through the file are also summarized. Specifically, humdrum indicates the number of terminated spines, the number of new spines introduced, the number of joined spines, the number of split spines, and the number of exchanged spines.

The following is a sample input that conforms to the Humdrum syntax.

Inventory of Interpretations: HUMDRUM FILE SUMMARY

Interpretations Occurrences
**inter 3
**foo 1
**bar 1
**ding 1
* 2
*bop 1

Inventory of data token signifiers: %()+-.034567:<>
ACILMPSTW^_
adeklnorstuwxy

Number of global comments: 14 Number of local comments: 4
Maximum # of concurrent spines: 3 Minimum # of concurrent spines: 3
Number of data records: 10 Number of null tokens: 4


Changes in number of spines:
New spines: 0
Terminated spines: 3
Split spines: 0
Joined spines: 0
Exchanges spines: 4

• Pertinent description in the Humdrum User Guide
• Index to Humdrum Commands
• Table for Contents for Humdrum User Guide