What does the word down-level mean?

I read an article here and it says:

But the versions for some browsers (like IE 10) aren't within those ranges any more. Therefore, ASP.NET sees them as unknown browsers and defaults to a down-level definition, which has certain inconveniences, like that it does not support features like JavaScript.

2 Answers 2


A Google search for “down-level” (with the quotes) yields the following in one of the early results:

down·lev·el / ˈdounˌlevəl/

  • adj. using an earlier version of software, hardware, or an operating system:
    there are still 600 million computers, many of them downlevel, that wouldn't have all of these vulnerabilities fixed.

Thus “defaults to a down-level definition” simply means “reverts to behaving as if it was an earlier version”. Because ASP.NET cannot reliably identify the browser version, it assumes it’s an early browser with minimal capabilities (so it delivers code which any browser should be able to cope with).

  • it's worth noting the general term "down-level" predates ASP.NET and is a familiar concept in the laser forms/print industry and may actually come from Post-Script / Print Control Language (PS/PCL) usage where "print level" defined capabilities and a "down level document" was typically a PS/PCL document with a lower "print level" than originally intended. extrapolating, the term more broadly identifies "any prior level of capabilities which can be substituted for the target level of capabilities", along with the standards path of HTML5 this definition of "down-level" works well.
    – wilson0x4d
    Jan 9, 2017 at 0:31

In this situation, down-level browsers are unclear definition browser. Maybe its standards are old and are not compatible to current standards. And when we try to run on these browses, they'll happen unexpected errors.

  • 1
    What does "unclearly definition browser" mean?
    – TrevorD
    May 20, 2013 at 12:19
  • 1
    There is a bug in the browser definition files that shipped with .NET 2.0 and .NET 4, namely that they contain definitions for a certain range of browser versions. so "unclear definition browser" is the browser that we couldn't find the exact error when we debug on this browser May 20, 2013 at 15:41

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