Hi, Stephan,
I know this answer comes way too late for you to notice, but I figured that I am not the only one who landed on this page after searching for the same question you posted. I was able to find the way to determine what the numbers mean. Here is how you do it:
1. Convert given decimal value to hexa, for instance:
(268435458)decimal = (0x10000002)hex
To do this conversion, feel free to use some online convertor,
this for example.
2. Execute the logical AND with 0xFF value (think of it as of the constant, there's more to it, but I will not go into details)
(0x10000002) AND (0x000000FF) = (0x0000002)hex
3. Compare your result with following list:
0 Link, 1 Typed, 2 (Auto) Bookmark, 3 (Auto) Subframe, 4 (Manual) Subframe, 5 Omnibar Generated, 6 Top Level / Start page, 7 Form submit, 8 Reload, 9 Keyword, 10 Keyword generated.