[texhax] plain TeX: `No room for a new \fam'

[Philip Taylor]

Donald Arseneau wrote:

> The way to "get round" it is to assign some dynamically, locally
> within the math, rather than globally.

Is it not the case, Donald (and I ask this from memory, so
may well be mistaken) that maths families are evaluated
only at the very end of the maths formula, so locally-
defined families would have to be encapsulated in non-maths
lists such as hboxes, vboxes, etc ?  If this is indeed the
case, then introducing such non-maths lists into a formula
may well have accompanying (and undesirable) effects on the
latter's spacing.

Philip Taylor