hhcolreg.dat stores information on collections on the machine.
You can access a DTD that describes this XML format or read on for a more humane description.
The outer element is XML, immediately inside this is the HTMLHelpDocInfo element, which is the true container for the other elements.
First in the HTMLHelpCollection element comes the meta-data element NextCollectionId. The value attribute of this element stores the value that the ColNum of the next Collection will have if another collection is ever added.
Then come the following three container elements; Collections, Locations and DocCompilations.
The Collections element contains any number of Collection elements. Each Collection element contains a single ColNum element and a single ColName element. The value attribute of the ColNum element stores a unique number that identifies the collection. The value attribute of the ColName element stores the full path to the .col file for this collection.
The Locations element contains any number of Location elements. Each Location element contains one of each of the LocColNum, LocName, TitleString, LocPath and Volume elements. The table below explains the content and purpose of the value attribute of each of these elements.
Element | Explanation |
LocColNum | The value attribute of the ColNum element of the Collection element that this Location element applies to. |
LocName | The name of this Location element. This is used in sub-elements of the LocationHistory element. |
TitleString | This is displayed in a dialog box when the user is prompted to insert the required media because it is not accessible by hh. |
LocPath | The full path where the location can be accessed. |
Volume | The volume label of the filesystem that the LocPath is stored on. |
The DocCompilations element contains any number of DocCompilation elements. Each DocCompilation element contains one of each of the DocCompId, DocCompLanguage and LocationHistory elements. The value attribute of the DocCompId element stores an identifier which is used in terminal Folder elements in the col files and is usually the stem of the CHM/CHI file for this element. The value attribute of the DocCompLanguage element stores the LCD. The LocationHistory element contains one of each of the ColNum, TitleLocation, IndexLocation, QueryLocation, LocationRef, Version, LastPromptedVersion, TitleSampleLocation, TitleQueryLocation and SupportsMerge elements, which are all described in the table below.
Element | Explanation |
ColNum | The collection number this DocCompilation is part of. |
TitleLocation | The full path to the CHM. |
IndexLocation | The full path to the CHI. |
QueryLocation | The full path to the CHQ. |
LocationRef | The LocName where the CHM/CHI are stored. |
Version | Numeric. Presumably a version of CHM. |
LastPromptedVersion | 0. Presumably the last Version that was installed before the previous one. |
TitleSampleLocation | The LocName where the samples for this CHM are stored. |
TitleQueryLocation | The LocName where the CHQ is stored. |
SupportsMerge | Numeric. Presumably whether or not the CHM has the other type of merging. |