Why missing characters and empty code points?

[James Kass]

On 2023-05-25 3:52 PM, admin--- via Unicode wrote:
> For example, why is MATHEMATICAL SCRIPT SMALL O missing and the assumed
> code point it would have, 1D4C4, is empty?  Yet 1D4C3 (MATHEMATICAL
> SCRIPT SMALL N) and 1D4C5 (MATHEMATICAL SCRIPT SMALL P) are defined.
> Makes no sense.  Thanks
U+2134 SCRIPT SMALL O

This character was already encoded before the math letters were added.  
The empty 1D4C4 preserves the expected and relative ordering with the 
other math character additions.