think about the notation environment and notatiendum macro.

[kohlhase]

these two are currently relatively ad-hoc, and their relation to the symdef process should be better understood. In particular, there is no clear indication on how \notatiendum should be used (and conflicting documentation and examples in statements.dtx.

All of this needs to be understood and cleaned up.

There is also an issue with markup practice: \symdef macros need to be done in the running text; probably best in notation or definition environments to have more locality.

[kohlhase]

Finally, there is the question whether there is a conceptual difference between notation declarations and definitions. But I guess that this should be clarified in OMDoc really. But sTeX is a good place with examples to think about this.