format-number of a value at or beyond 2^53 ran an unguarded
Double-to-Int conversion, a fatal trap reachable from user data; a
fraction picture beyond 15 places overflowed the scale conversion the
same way; and xsl:number value= beyond 2^53 trapped identically.
Digit extraction clamps fraction places to 15 (the 2^53 exactness
bound), pads back to the picture's minimum, renders out-of-range
integers through the exponent expander, and xsl:number falls back to
plain number rendering outside [1, 2^53). Sort-key rows always carry
one key per sort. Regression tests cover all three trap paths.
The picture parses into affixes, number part, and the negative
subpattern: literal prefixes and suffixes pass through, the negative
subpattern's affixes apply (with the default minus when it has no
distinguishing ones), per-mille and percent multiply and stay literal,
the grouping size derives from the pattern's last grouping separator,
colliding decimal/grouping separators read as grouping, and U+00A4
renders as the en-US currency symbol. Digit extraction now uses one
scaled rounding and integer arithmetic, eliminating per-digit float
drift. Xalan numberformat 30 -> 1; baseline 475 -> 446.
format-number now honors named and default decimal formats: the decimal
separator, grouping separator, percent, minus sign, zero-digit (for
non-Latin digit sets), NaN, and infinity symbols come from the chosen
xsl:decimal-format, in both the picture and the output. FormatNumber is
parameterized over the symbol set and the formats thread through the
function table; folded across include/import.
