This code system http://hl7.org/fhir/v3/Charset defines the following codes:

CodeDisplayDefinition
EBCDICEBCDICHL7 is indifferent to the use of this Charset.
ISO-10646-UCS-2ISO-10646-UCS-2Deprecated for HL7 use.
ISO-10646-UCS-4ISO-10646-UCS-4Deprecated for HL7 use.
ISO-8859-1ISO-8859-1HL7 is indifferent to the use of this Charset.
ISO-8859-2ISO-8859-2HL7 is indifferent to the use of this Charset.
ISO-8859-5ISO-8859-5HL7 is indifferent to the use of this Charset.
JIS-2022-JPJIS-2022-JPHL7 is indifferent to the use of this Charset.
US-ASCIIUS-ASCIIRequired for HL7 use.
UTF-7UTF-7HL7 is indifferent to the use of this Charset.
UTF-8UTF-8Required for Unicode support.