[TYPO3-templavoila] How to modify tt_content in Datastructure?

[H. Reimers]

Hi at all....

i'm using this TS to append a link to the content if the header is linked to 
a page...

  tt_content.text.20.stdWrap.append = COA
  tt_content.text.20.stdWrap.append {
      10               = TEXT
      10.value         = mehr
      10.fieldRequired = header_link

      10.typolink {
          parameter.field = header_link
          ATagParams      = class="headerLink"
          ATagBeforeWrap  = 0
          wrap            = <span class="headerLink">|</span>
      }
  }

but now i'm only want to use this for only one row of my TV datastructure 
like field_leftContent...

how could i do this?

thanks a lot...

hendrik