# \above

Plain-TeX infix generalized fraction with an explicit rule thickness between the left and right formulas.

https://texform.dev/latex/commands/above

## Metadata

| Field | Value |
| --- | --- |
| Topic | [Fractions and roots](https://texform.dev/latex/topics/fractions-roots) |
| Packages | base |
| Allowed mode | math |
| Tags | discouraged |
| Commonality | low |
| Kind | infix |

## Syntax

### base

Argument specification: `m:L`

Plain-TeX infix generalized fraction with an explicit rule thickness between the left and right formulas.

## Examples

```latex
a \above 1em b
```

[Open in Playground](https://play.texform.dev/?input=a+%5Cabove+1em+b)

```latex
a \above {1em} b
```

[Open in Playground](https://play.texform.dev/?input=a+%5Cabove+%7B1em%7D+b)

## Renderer support

| Package | MathJax | KaTeX | XeTeX |
| --- | --- | --- | --- |
| base | full | full | full |

## Usage frequency

<0.01% of formulas in the measured corpus contain this entry, rank 252 of 263 entries with frequency data.

## In TeXForm

TeXForm parses this entry as infix syntax; the package determines its argument specification.

### Discouraged in base

This is a plain-TeX infix generalized fraction primitive. LaTeX users generally prefer brace-delimited commands such as \genfrac.

```latex
$1 \above $2 $3 -> \genfrac{}{}{$2}{}{$1}{$3}
```

\genfrac is the standard LaTeX generalized-fraction command, uses explicit braced arguments, and avoids the ambiguous grouping of infix primitives.

### [base/above-to-genfrac](https://texform.dev/rules/base/above-to-genfrac)

Rewrite above to a thickness-preserving genfrac form.

Level: authoring. Fidelity: render.

```latex
#1 \above #2 #3
```

→

```latex
\genfrac{}{}{#2}{}{#1}{#3}
```

```latex
\sum_{i=1}^{m} a_i x^i \above 1.2pt \prod_{j=1}^{n}(1+y_j)
```

→

```latex
\genfrac{}{}{1.2pt}{}{\sum_{i=1}^{m} a_i x^i}{\prod_{j=1}^{n}(1+y_j)}
```

## Equivalent forms

```latex
\genfrac{}{}{$2}{}{$1}{$3}
```

exact. 

## See also

- [\\abovewithdelims](https://texform.dev/latex/commands/abovewithdelims)
- [\\atop](https://texform.dev/latex/commands/atop)
- [\\atopwithdelims](https://texform.dev/latex/commands/atopwithdelims)
- [\\brace](https://texform.dev/latex/commands/brace)
- [\\brack](https://texform.dev/latex/commands/brack)
- [\\choose](https://texform.dev/latex/commands/choose)
- [\\over](https://texform.dev/latex/commands/over)
- [\\overwithdelims](https://texform.dev/latex/commands/overwithdelims)

## Test cases

### base

| Input | Case | MathJax | KaTeX | XeTeX |
| --- | --- | --- | --- | --- |
| a \above 1pt b | Positive: baseline | Pass | Pass | Pass |
| a \above {a} b | Negative: neg:L[0] | Fail | Fail | Fail |