The control words you are looking for are \clwWidthN and \clftsWidthN
Microsoft RTF v1.9.1 specification :
- \clwWidthN Preferred cell width. Overrides \trautofitN. - \clftsWidthN Units for \clwWidthN: - 0 : Null. Ignore \clwWidthN in favor of \cellxN (Word 97 style of determining cell and row width). - 1 : Auto, no preferred cell width, ignores \clwWidthN if present; \clwWidthN will generally not be written, giving precedence to row defaults. - 2 : Percentage (in 50ths of a percent). - 3 : Twips.
Thus, in your case, you can simply use \clftsWidth1 (automatically set the width) or set your preferred percentages yourself, for example. \clwWidth2\clwWidth2500 (2500 = 50%)
Auto Width
\trowd \trautofit1 \intbl \clftsWidth1\cellx1 \clftsWidth1\cellx2 \clftsWidth1\cellx3 {a\cell b\cell c\cell }
40% - 30% - 30%
\trowd \trautofit1 \intbl \clftsWidth2\clwWidth2000\cellx1 \clftsWidth2\clwWidth1500\cellx2 \clftsWidth2\clwWidth1500\cellx3 {a\cell b\cell c\cell }
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