In HL7 messaging, the separator characters are known as the message delimiters or special encoding characters.
Field separator, aka pipe
Component separator, aka hat
Field repetition separator
The first two fields in the MSH segment define the separator characters to be used throughout the HL7 message. The MSH-1 field defines the field separator, and the MSH-2 field defines the other separator characters for the message in the following order: component, field repeat, escape character, and subcomponent. Here’s an example of an MSH segment with the defined separator characters in MSH-1 and MSH-2: