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CHM is an extension for the Compiled HTML file format, most commonly used by Microsoft’s HTML-based help program. It may contain many compressed HTML documents and the images and JavaScript they link to. CHM features include a table of contents, index, and full text searching. Most of Aerotech’s Help Files are in CHM format.
If you can open the Help file and see navigation (table of contents) in the left pane, but the right pane is empty or shows a warning message, try this:
SECURITY WARNING: “The CHM viewer component is not properly registered on your PC.”
If you see this warning, clear the checkbox next to “Always ask before opening this file”.
SECURITY WARNING: “The system file
.ocx is missing, corrupted, or unregistered.”
System files smay sometimes “unregister” themselves when you install Windows service packs. To resolve, run regsvr32 hhctrl.ocx in the command line (Start > Run) to register the library in the system.
Your CHM files are stored in the folder with ‘#’ (hash) character in the path.
C# developers may discover that their documentation and e-books in CHM format cannot be opened because they store their CHM files in directories such as ‘C:-books#'. The hash character signifies an anchor in HTML so the CHM viewer fails to resolve the path properly and to retrieve the content. To resolve, remove the’#’ (hash) character from the directory name. Also avoid using ‘?’, ‘&’, and ‘+’ characters in directory names.
The CHM file is in the restricted Internet zone
When a CHM file that you are trying to access is stored remotely, e.g. on the network drive or on a remote server, you may also have problems. If the associated security zone is restricted, then CHM files won’t be displayed as well. To resolve, modify the ItssRestrictions registry entry to enable a specific security zone.
0 = My Computer
1 = Local Intranet Zone
2 = Trusted Sites Zone
3 = Internet Zone
4 = Restricted Sites Zone
Warning: Enable only those security zones that you trust. Do not enable security zones about which you are not sure.
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