0 : Ctrl+Alt+Letters
1 : Alt+Letters
2 : Letter only
3 : Letters - with search dialog
The number of the selected option is the value of the "AltSearch" key in the "[Configuration]" section of "wincmd.ini" file. I suggest to add one more option to support the Windows standard behavior for lists:
4 : Windows List Standard
You can encounter "Windows List Standard" behavior in almost any list or drop-down list of any Windows application, for example in the lists of the commonly used "Open" or "Save As" dialogs, in the "Folders" pane and in the file pane of the Windows Explorer, in the file list of WinRAR V3.11, in the "Bookmark Manager" of Mozilla V1.2.1 and so on.
In my opinion the standard behavior is very simple, but nevertheless quite efficient in most cases because you just can quickly hammer the very same key and you can fully concentrate on the screen at the same time. After the first stroke when the focus is usually already close to your desired file then you can see immediately that you have to press the key for instance 3 more times. Furthermore the feature doesn't even require that you have both hands down on the keyboard. It is also useful if you are not an incredibly fast 10-fingers typist or when you have one hand on the mouse. Within quite large directories containing roughly 250 files with equally distributed initial letters you can focus a specific file on average by just pressing its initial letter 5 times!
Until recently I was convinced that "Letter only" is supposed to offer the Windows standard behavior, but I was wrong (Black Dog almost killed me

Letter only : Like in file manager/Explorer, typing a letter jumps to the next file starting with that letter. … You can type the first few characters of a file, not only the first letter. Total Commander will 'forget' the typed letters after about 1 second delay.
I find the behavior of "Letter only" mode irritating because it destroys the biggest advantage of the standard behavior and if you type approximately at a rate of 1 character per second you are not sure what exactly TC is searching for.