The exception indexing function is used to create an array or a table for which unassigned access is illegal. Any object can be stored in an array or a table that uses the exception indexing function, but indexing into the array or table with an index for which no entry exists raises an exception.

Note: The command array has been superseded by Array.

$T≔\mathrm{table}\left('\mathrm{exception}'\,\left[a=1\,b=2\right]\right)$

$T≔table\left(\mathrm{exception}\,\left[a=1\,b=2\right]\right)$

$T\left[a\right]$

$1$

$T\left[c\right]$

Error, (in `index/exception`) unassigned table entry [c]

$T\left[a,b\right]$

Error, (in `index/exception`) unassigned table entry [a, b]