{$INCLUDE Common}      // Inserts the contents of Common.pas into the current unit
{$I Common}            // Same as the previous line, but in a shorter form
{$INCLUDE_ONCE Common} // Inserts the contents of Common.pas into the current unit only if not included already
{$FILTER Common}       // Inserts the contents of Common.pas into the current unit after filtering
{$F Common}            // Same as the previous line, but in a shorter form