Hjälp:-
{{[[Mall:{{{1}}}|{{{1}}}]]}}
Template to put centered dash inside table cell.
See also Help:Template#Table cell templates.
Example
[redigera wikitext]{| class="wikitable"
|-
! Long title text 1 !! Long title text 2 !! Long title text 3
|-
| rowspan="2" {{-}} || colspan="2" {{-}}
|-
| {{-}} || Regular text
|}
| Long title text 1 | Long title text 2 | Long title text 3 |
|---|---|---|
| rowspan="2" | colspan="2" | |
| Regular text |