I seen at different places if a field has a name "LinkFilename" then while trying to get its value using CAML query or any other way, developers put it as "ows_LinkFilename", can someone explain it to me please.

And also how can we check if a fields exists or not using CAML query.

2 Answers 2


When communicating using services, SharePoint uses a DLL named OSWSSVR.DLL. This dll is responsible for many things including working with list data. This dll works with an XML namespace named OWS and uses it to recognize CAML data. So this prefix is added to the data returned in the web services.


1- Page Rendering Elements
2- Overview of the SharePoint Team Services Architecture

I don't think it is possible to check if a field exists using CAML queries, because CAML queries relies on fields and field values to get data. But if you want you can catch the exception thrown when queriying using a non existing field.

I didn't find any exact references but you can start searching using these links:

1- Link 1
2- Link 2

  • cheers, can you provide any example or link for non existing field as well please. Commented Nov 6, 2012 at 13:38

ows_ is the SharePoint out of the box field prefix. It has been around since the start of time pretty much, and even though it is used for SharePoint Team Services it has kept the OWS name (Office Web Server) and why such things as search still comes from office.

[update - I know the answer was accepted but I thought I would put some history in here I dug it up for this post]

It was first SharePoint Portal Server before Team Foundation Server but the project was Codenamed Office Server which is where it all stems from.

Names of SharePoint:

Office Server (This came from FrontPage and Team Pages)

Tahoe (This was Exchange, Dashboard, Portal, Search and Document management)

SharePoint Portal Server

SharePoint Team Services

Windows SharePoint Services 2.0

Windows SharePoint Services 3.0

Microsoft SharePoint Foundation 2010

And that is how we still have ows floating around. Why we still have access through FrontPage RPC and why Office Portal controls the searching functionality.


  • 2
    Thanks! I've always been curious about the 'ows' thingy!
    – Benny Skogberg
    Commented Nov 21, 2013 at 8:50

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