docs: scienting-math/1 tree kinds prescript and mark

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_017R7sgDNvUGWY2zFPCq2JH6

spec/09-figures-tables-equations.md

@@ -74,6 +74,8 @@ Brackets group and leave no node.
 | `times`, `div`, `op` | Two operands, after the operator's command for `op` | `\times`; `/` or `\div`; any other binary operator. |
 | `frac`, `binom`, `sqrt`, `root` | Numerator and denominator; the radicand, after the index for `root` | Fractions, binomials and roots. |
 | `pow`, `sub`, `prime`, `fact` | The base, and the script for `pow` and `sub` | Scripts, primes and factorials on what is not a symbol. |
+| `prescript` | The lower script, the upper script, the base | Scripts before their base, as in the isotope `^{31}\text{P}`. |
+| `mark` | The sign or operator | A sign or operator with no operand: a charge (`x^{+}`), the radical dot of `\cdot\text{OH}`, a formula cut by its converter. |
 | `apply` | The function's command, its argument, and its subscript if any | A named function: `\cos(x)`, `\log_{2} n`, `\max_{i} x_{i}`. |
 | `lim` | The command, what is under it, the body | `\lim`, `\liminf` and `\limsup`. |
 | `sum`, `prod`, `coprod`, `int`, `iint`, `iiint`, `oint`, `bigcup`, `bigcap` | The lower limit, the upper limit, the body | A big operator, whose body runs to the next sign outside brackets. |