Envelope definition - Standards for electronic data interchange within the UK Blood Transfusion Services - Chapter 25

The envelope definition defines the content of the first and last lines of the file/transmission (see Table 25.1 and 25.2).

The first or header line contains an identifier specifying that this is a message complying with a UKBTS specification, the date and time generated, the source and destination of the message, and the protocol number which identifies the relevant protocol to which the message conforms.

Source and destination identifiers for the Blood Establishments will be the ISBT 128 collection facility identification code. It is anticipated that hospital blood banks will use the identifier assigned by their local Blood Establishment.

The terminator line contains a record count indicating the total number of message lines excluding the header and terminator lines, and a standard terminator message.

Table 25.1: Envelope definition – header line

Field	Length	Description	Format	Mandatory?
Field 1	Length 5	Description Line number	Format NNNNN (see note 1)	Mandatory? Yes
Field 2	Length 10	Description Fixed text	Format ‘UKBTSSTART’	Mandatory? Yes
Field 3	Length 8	Description Date	Format YYYYMMDD	Mandatory? Yes
Field 4	Length 4	Description Time	Format HHMM	Mandatory? Yes
Field 5	Length 6	Description Protocol number	Format NNNNNN (see note 2)	Mandatory? Yes
Field 6	Length 6	Description Source ID	Format XXXXXX	Mandatory? Yes
Field 7	Length 6	Description Destination ID	Format XXXXXX	Mandatory? Yes
Field 8	Length 2	Description Checksum	Format NN	Mandatory? Yes
Field 9	Length 1	Description Terminator	Format Carriage return	Mandatory? Yes

Notes on Table 25.1

1. Always 00001 for header line.
2. Allocated by the Standing Advisory Committee on Information Technology (SACIT).

Table 25.2: Envelope definition – footer line

Field	Length	Description	Format	Mandatory?
Field 1	Length 5	Description Line number	Format NNNNN	Mandatory? Yes
Field 2	Length 9	Description Fixed text	Format ‘UKBTSSTOP’	Mandatory? Yes
Field 3	Length 5	Description Number of records	Format NNNNN	Mandatory? Yes
Field 4	Length 2	Description Checksum	Format NN	Mandatory? Yes
Field 5	Length 1	Description Terminator	Format Carriage return	Mandatory? Yes