126 | Chapter 3: The Registry
The system Windows uses to keep track of its file types has
been around for years and has survived a bunch of different
Windows versions. As a result, you??™ll see a lot of inconsistencies.
Sometimes, for instance, the meat of a file type is actually
in the extension key (e.g., HKEY_CLASSES_ROOT\.scp)
rather than the file type key. Because Windows still allows
this, some developers still do it this way, and in turn, you??™ll
have to deal with it. Although most file types do follow the
structure laid out on these pages, don??™t be surprised if you
see something that doesn??™t belong and still works.
A typical file type key (e.g., HKEY_CLASSES_ROOT\txtfile) has a few values and
subkeys, most of which appear in Figure 3-12.
First, the (Default) value contains the name of the type, the text that
appears in Windows Explorer??™s Type column.
If a value named AlwaysShowExt is present in this key, the extension for this
file type will be displayed in Explorer, even if you??™ve elected to hide your
filename extensions (a setting explained at the beginning of this section). A
related value, NeverShowExt, appears in a few file type keys??”such as those
for Windows Shortcuts (.lnk files), Internet Shortcuts (.url files), and
Explorer Commands (.scf files)??”and instructs Explorer to always hide the
extensions for these files, regardless of your preferences.
You??™ll also see some other values such as EditFlags, FriendlyTypeName, and
InfoTip that are fairly inconsequential, but it??™s the stuff in the following
three subkeys that??™s responsible for most of the magic:
Figure 3-12.
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