c# operator :

what does "showOtherVersions: false" mean in
this.discoService.getItemPageInfo(this.discoLoginParams, discoParams, catalogObject,
showOtherVersions: false,
showOtherVersionsSpecified: true,
showPreviews: false,
showPreviewsSpecified: true);

I looked in msdn but didn't found such operator?

you also think that asking the same question in different parts of the forum increases the chance that someone answers it? but formulating your question more precisely is better then multiple threads

It's not an operator, it is named parameters:
http://msdn.microsoft.com/en-us/library/dd264739.aspx