I see no such limit practically or in any documentation.

Code:
alias a {
  bset &b 5000 1
  hadd -mb table item &b
  echo -ag $hget(table,item,&c)
  echo -ag $bvar(&c,0)

  echo -ag -
  var %v = $+($str(0,4100),1)
  hadd -m table item2 %v
  echo -ag $hget(table,item2)
  
  hadd -m table %v 1
  echo -ag $hget(table,%v)
}