\MRTtabRepeatColumns as documented macro

Doc/tex/doc_MRTtab.tex

@@ -286,6 +286,16 @@ provided:
   vertical skip which reveals the lines (issuing
   \verb|\noalign{\vskip\arrayrulewidth}|).  It is also used by \cs{MRTcline}.
 \end{describemacro}
+
+\begin{describemacro}{MRTtabRepeatCols}
+  This macro is to be used in column definitions of \env{tabular}s or
+  \env{array}s and other macros and environments using these internally (e.g.
+  \env{MRTtabular} and \env{MRTtable}). The effect is that the column
+  definitions which follow this macro are repeated indefinitely to match the
+  required columns for the tables body. E.g., \bverb|l \MRTtabRepeatCols c| does
+  set the first column left aligned and every following column centred. It has
+  to be preceded by at least one valid column definition.
+\end{describemacro}
 %<<<
 
 \section{Options}\label{sec:tab:options}%>>>

MRTtab/MRTtab.sty

@@ -27,7 +27,7 @@
 
 %% package variables >>>
 %%=============================================================================
-\newcolumntype{?}{!{\d@llarend&\span\@gobbletwo}}
+\newcolumntype{\MRTtabRepeatCols}{!{\d@llarend&\span\@gobbletwo}}
 \definecolor{tablegray}{gray}{0.85}
 \tl_new:N  \l_MRTtab_tmpa_tl
 \int_new:N \l_MRTtab_tmpa_int
@@ -141,7 +141,7 @@
     ,caption         .tl_set:N           = \l_MRTtab_table_cap_tl
     ,cap             .meta:n             = { caption = { #1 } }
     ,columns         .tl_set:N           = \l_MRTtab_table_col_tl
-    ,columns         .initial:n          = { l?c }
+    ,columns         .initial:n          = { l\MRTtabRepeatCols c }
     ,col             .meta:n             = { columns = { #1 } }
     ,env~begin       .tl_set:N           = \l__MRTtab_env_begin_tl
     ,env~end         .tl_set:N           = \l__MRTtab_env_end_tl