SAP UNICODE KEYS documentation, setup help and example usage

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Specifying the Key for Tables Accesses
A syntax error occurs in a Unicode program if you use the obsolete statements LOOP AT dbtab , READ TABLE dbtab or READ TABLE itab unless the key is purely character-type.
A syntax or runtime error occurs for the READ TABLE itab statement, if the standard key of the internal table contains types X or XSTRING fields. With this READ variant, the system determines actual table key by hiding all the components filled with spaces. To do this, you must make sure that all the components of the key can be compared with SPACE in the Unicode program.
A syntax or runtime error occurs when you access the database with a generic key unless the key is purely character-type. This affects the following commands:
READ TABLE dbtab ...SEARCH GKEQ ...
READ TABLE dbtab ...SEARCH GKGE ...
LOOP AT dbtab ...
REFRESH itab FROM TABLE dbtab.
The actual table key is determined by truncating the closing spaces of the database key in these statements. To do this, you must make sure that all the components of the key can be compared with SPACE in the Unicode program.