what's the width unit in webi report structure(bi 4.1)

In order to retrieve the column width ,I get a xml structure using the rest api  /reports/reportid/specification.However the col width is not px unit.

<TDCELL bId="85" width="3034" height="900" autofitHeight="no" autofitWidth="no" leftPadding="252" rigthPadding="252" bottomPadding="360" topPadding="288" what="text" colspan="1" rowspan="1">

            <STYLE>

              <BACKGROUND fill="none"/>

              <BORDER side="bottom" width="0" style="none"/>

              <BORDER side="top" width="0" style="none"/>

              <BORDER side="left" width="0" style="none"/>

              <BORDER side="right" width="0" style="none"/>

              <FONT color="#000000" size="13" bold="no"/>

              <TEXTHALIGN value="right"/>

            </STYLE>

            <CONTENT>test</CONTENT>

          </TDCELL>

I wonder what the width number really means and how to convert it into px unit.

thks a lot.