title: What is the default size of a STRING in IEC61131-3
body: <p>I inherited a PLC program written in IEC 61131-3 structured text. I just noticed that it has a mixture of <code>STRING</code> variables, and a few <code>STRING(15)</code> variables. It suggests that IEC61131-3 declares its strings with a pre-defined length (does it?) and that there may be a default length (is there?) It makes me wonder if some of the strange string behaviour I have observed comes from strings overflowing their buffers and the excess being ignored (possible?)</p>
  
  <p>Ideally, please support any answer(s) with link(s) to a readily accessible IEC61131-3 reference so that one can browse it for further details of <code>STRING</code> and other IEC 61131-3 data types.</p>