function CheckLen()
{
	fieldToCheck = 'popis';
	fieldMaxLength = 300;
	
	for(var i=0;i < document.forms.length; i++)
	{
		for(j=0;j < document.forms[i].elements.length; j++)
		{
			if(document.forms[i].elements[j].name == fieldToCheck)
			{
				StrLen = document.forms[i].elements[j].value.length;
				if ( StrLen > fieldMaxLength )
				{
					document.forms[i].elements[j].value = document.forms[i].elements[j].value.substring(0,fieldMaxLength);
					CharsLeft = fieldMaxLength;
				} else {
					CharsLeft = StrLen;
				};
				var CharsLeft1 = fieldMaxLength - CharsLeft;
				
				// Updating reste field
				document.forms[i].reste.value = CharsLeft1;
			}
		}
	}

};