OST is closed for business but its spirit survives on my blog.
As I understand it, postmodernism dissolves the objective-subjective polarity. When everything is subjective, nothing is subjective (it has no binary opposite - which would be structuralism whereas this is poststructural).
Of course, you or I may be committed to one “truth” rather than another, but there is no external basis for this available.
This is different from the Isaiah Berlin position which was about competing objective truths, which was a harder form of liberalism. The postmodern position says that they are not objective, and there is not objectivity available (and thus no subjective limitation).