When using both brackets and braces together in an HL7 message, what does it indicate about the enclosed segment?

The use of both brackets and braces in an HL7 message signifies that the enclosed segment is both optional and can be repeated. In HL7 syntax, brackets are used to denote optional segments or fields, while braces indicate that the contained elements can be repeated. When you find a segment wrapped in both, it explicitly signals that this segment is not mandatory (optional) and can also appear multiple times (repeating) within the message. This combination allows for greater flexibility in how the data is structured and transmitted, accommodating various scenarios where certain pieces of information might not be essential or where multiple instances of that information may need to be included.