ふーむ，しらん間に HFS+ が拡張されてたのね．

• Technical Notes TN1150 - HFS Plus Volume Format (revised version on March 2, 2004)

とりあえずは

HFSX is an extension to HFS Plus to allow additional features that are incompatible with HFS Plus. The only such feature currently defined is case-sensitive filenames.

ってことだけの違いらしいんやけど．

それにしても，

An HFSX volume may be either case-sensitive or case-insensitive. Case sensitivity (or lack thereof) is global to the volume; the setting applies to all file and directory names on the volume. To determine whether an HFSX volume is case-sensitive, use the keyCompareType field of the B-tree header of the catalog file. A value of kHFSBinaryCompare means the volume is case-sensitive. A value of kHFSCaseFolding means the volume is case-insensitive.

というのはどうなんやろう．後方互換性の為とは思えないし，なんか無駄にチェックルーチンを増やしている様な気もしますが，はてはて．

ともあれ，

In an Apple partition map, the partition type (PMPartType) of an HFSX volume is set to "Apple_HFSX".

の部分だけは絶対に忘れへん様に備忘録．