UD - Unsave Document

PURPOSE

Unsaves a sequence of registers from a document file.

SEE ALSO

UD E	[Unsave Document - End]
UD N	[Unsave Document - get key Numbers]
UD S	[Unsave Document - Sequential search]
UD IC	[Unsave Document - In Core]

USAGE

.OPERATION: UD X0,X15,X20,X50

<or>
UD -1,X40

.DOCUMENT FILE: DOC001
[Enter the name of the file where the registers are to be found.]

[The first register or number after 'UD' is used as a key for retrieving the desired register set stored there previously. In the above example, let us assume X0 has the value 4. The system then searches the document file for the last (or, in the case of 'UD S', next) entry under this key number. If this entry consisted of the line

4 3 -1.5 30.8 0.0

then the values -1.5, 30.8, and 0.0 are put into the registers X15, X20, and X50, respectively.]

[If more registers are specified in the 'UD' operation than were used in the 'SD' operation creating the entry, an error message is printed out. In the above example,

UD X0,X15,X20,X50,X28

would produce an error statement because the number of registers exceeds the number in the corresponding 'SD' operation.]

NOTES

1. Sequential search 'UD S' is much faster than non-sequential, and should be used whenever it is certain that no updates have occurred.

2. If the specified key is -999 < key < 0 then the operation searches the document file for a line preceeded by a semicolon similar to a comment. This line is treated as as a regular line containing a special key and list of registers. This allows the retrieval of a limited set of values like rotation angles which are somehow associated with the contents of the file. The normal retrieval process (positive keys) treats these lines like comments.

3. The document file is left open until closed with 'UD E' or until another document file is used with 'UD'. This saves time when there are multiple accesses.

SUBROUTINES

UDOC, OPENDOC, UNSAV, LUNDOC

CALLER

DRIV3