## Character Sets, Code Sets, and Code Set Conversion

A character set is a group of characters, such as the English alphabet, Japanese Kanji, and the European character set. To enable world-wide connectivity, DCE guarantees that a minimum group of characters is supported in the DCE. The DCE RPC communications protocol ensures this guarantee by requiring that all DCE RPC clients and servers support the DCE Portable Character Set (PCS). The Introduction to OSF DCE lists the characters in the DCE PCS. The IDL base type specifiers char and idl_char identify DCE PCS characters.

A code set is a mapping of the members of a character set to specific numeric code values. Examples of code sets include ASCII, JIS X0208 (Japanese Kanji), and ISO 8859-1 (Latin 1). The same character set can be encoded in different code sets; consequently, a DCE can contain RPC clients and servers that use the same character set but represent that character set in different numeric encodings. Code set conversion is the ability for a DCE RPC client or server to convert character data between different code sets.

The DCE RPC communications protocol, through the Network Data Representation (NDR) transfer syntax, provides automatic code set conversion for DCE PCS characters encoded in two code sets: ASCII and EBCDIC. The RPC communications protocol automatically converts character data declared as char or idl_char between ASCII and EBCDIC encodings, as necessary, for all DCE RPC clients and servers.

The DCE RPC communications protocol does not provide support for the recognition of characters outside of the DCE PCS, nor does it provide automatic conversion for characters encoded in code sets other than ASCII and EBCDIC.

However, DCE RPC does provide IDL constructs and RPC runtime routines that programmers can use to write RPC applications that exchange non-PCS, or international, character data that is encoded in code sets other than ASCII and EBCDIC. These features provide mechanisms for international character and code set evaluation and automatic code set conversion between RPC clients and servers. Using these features, programmers can design their applications to run in a DCE that supports multiple heterogeneous character sets and code sets.

The next topic describes the remote procedure call execution model when the DCE RPC features for character and code set interoperability are used.

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