MCU unsigned char code/unsigned char idata variable

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Unsigned char data variable name. Why does one more data keyword exist?

I checked the help document. PDF, found the answer on page91:

Keyword: data, Code, defines the memory space for variable storage.

Appendix:

The storage type in C51

Code: program storage area (64 KB ),

Data: directly addressable internal data storage zone (B)

Idata: inner data storage area (256b) that cannot be directly addressable)

Bdata: addressable internal data storage zone (16 B)

Xdata: external data storage zone (64 KB)

Pdata: External paging Data Storage Area