Clean up immutable regions section a bit

docs/manual/format.md

@@ -258,33 +258,29 @@ starts at byte 592: "00 09 9b 31", which is 629553).
 
 ### Immutable header regions
 
-The header data structure has changed in rpm-4.0.[12] to preserve the
-original header from a package. The goal is to keep the original
-header intact so that metadata can be verified separately from the
-payload by the RHN up2date client and by the rpm command line verify
-mode using signatures saved in the rpm database. I believe the change
-is entirely forward and backward compatible, and will not require
-any artifacts like changing the version number of packaging or 
-adding an "rpmlib(...)" tracking dependency. We'll see ...
+One useful feature of RPM is the ability to preserve the original
+header from a package, so that metadata can be verified separately
+from the payload, e.g. using signatures saved in the rpm database.
+This ability was added in RPM 4.0.12 with the concept of immutable
+header regions.
 
-Here's a short description of the change. An rpm header has three sections:
+A short description of the implementation is as follows.
+As described above, an rpm header has three sections:
 ```
 	1) intro		(# entries in index, # bytes of data)
 	2) index		16 byte entries, one per tag, big endian
 	3) data			tag values, properly aligned, big endian
 ```
-
 Representing sections in the header (ignoring the intro) with
 ```
 	A,B,C			index entries sorted by tag number
 	a,b,c			variable length entry data
-	| 			boundary between index/data
+	|	  			boundary between index/data
 ```
 a header with 3 tag/value pairs (A,a) can be represented something like
 ```
 	ABC|abc
 ```
-
 The change is to introduce a new tag that keeps track of a contiguous
 region (i.e. the original header). Representing the boundaries with
 square/angle brackets, an "immutable region" in the header thus becomes
@@ -339,11 +335,6 @@ What made header regions trickier yet is the desire to have an implementation
 that is both backward and forward compatible. I won't bore you with the
 tedious details.
 
-However, even after doing regressions against supported Red Hat releases,
-there's a Great Big Universe of rpm packages out there, and I'm *very*
-interested in hearing (as bug reports against rpm at http://bugzilla.redhat.com)
-about any and all problems with header regions in rpm-4.0.1.
-
 ## Payload
 
 The Payload is currently a cpio archive, typically compressed using

docs/manual/index.md

@@ -41,8 +41,7 @@ title: rpm.org - RPM Reference Manual
 * [Plugin API](plugins.md)
 
 ### Package Format
-* [RPM v3 file format](format.md)
-* [RPM v4 header regions](hregions.md)
+* [RPM v4 file format](format.md)
 * [RPM v4 signatures and digests](signatures_digests.md)
 
 ### Documentation