Tier 1 (Gen) Dep Extension Online - Surname and Givenname

Hi,
I am trying to apply online my wife's Tier 1(Gen) extension ( I have ILR already). My wife's name in passport is in the format - Given Name: ABC XYZ -(surname and given name in one field and surname field empty). But when I go to the online application form, it does not let me leave Surname field empty. During the last extension we applied using paper form and we did not fill the Surname part in the form and that worked well. But in the online form , since Surname field is required filed, Not sure what to fill in there. Could you please suggest? I have gone through similar questions like this in this forum and did not find any answer specific to the online application. Hence I am writing this post.
Thanks in advance for your response.

Fill the "xyz" as surname if that suits the surname. HOW is aware of name anomalies in some passports.

CR001 wrote:Fill the "xyz" as surname if that suits the surname. HOW is aware of name anomalies in some passports.

Thanks a lot for the response. I thought the name should appear exactly as in passport and that made the confusion. Sure, I will split it as - Given Name: ABC, Surname: XYZ.. Hope its not an issue.
Thanks