[PhilJ]

try this (v4.0.14) - it should remove apostrophes from all four fields.

payment_po.tpl

{* $Id: payment_po.tpl,v 1.8.2.2 2004/08/25 06:06:17 max Exp $ *}

<script language="javascript"> 
<!-- Begin 
function ignoreChar(string) { 
var temp = ""; 
string = '' + string; 
//-------------------------------------------- 
//--- Change the character within the quotes 
//--- to whatever character you want excluded. 
splitstring = string.split("'"); 
//-------------------------------------------- 
for(i = 0; i < splitstring.length; i++) 
temp += splitstring[i]; 
return temp; 
} 
// End --> 
</script> 

<SCRIPT type="text/javascript">
requiredFields[0] = new Array("PO_Number", "{$lng.lbl_po_number}");
requiredFields[1] = new Array("Company_name", "{$lng.lbl_company_name}");
requiredFields[2] = new Array("Name_of_purchaser", "{$lng.lbl_name_of_purchaser}");
requiredFields[3] = new Array("Position", "{$lng.lbl_position}");
</SCRIPT>

<TABLE width="100%" border="0" cellspacing="0" cellpadding="2">

<TR valign="middle">
<TD height="20" colspan="3">{$lng.lbl_po_information}<HR size="1" noshade></TD>
</TR>

<TR valign="middle">
<TD align="right">{$lng.lbl_po_number}</TD>
<TD><FONT class="Star">*</FONT></TD>
<TD nowrap>
<INPUT type="text" size="32" id="PO_Number" name="PO_Number" onKeyup="this.value=ignoreChar(this.value);">
</TD>
</TR>

<TR valign="middle">
<TD align="right">{$lng.lbl_company_name}</TD>
<TD><FONT class="Star">*</FONT></TD>
<TD nowrap>
<INPUT type="text" size="32" id="Company_name" name="Company_name" onKeyup="this.value=ignoreChar(this.value);">
</TD>
</TR>

<TR valign="middle">
<TD align="right">{$lng.lbl_name_of_purchaser}</TD>
<TD><FONT class="Star">*</FONT></TD>
<TD nowrap>
<INPUT type="text" size="32" id="Name_of_purchaser" name="Name_of_purchaser" onKeyup="this.value=ignoreChar(this.value);">
</TD>
</TR>

<TR valign="middle">
<TD align="right">{$lng.lbl_position}</TD>
<TD><FONT class="Star">*</FONT></TD>
<TD nowrap>
<INPUT type="text" size="32" id="Position" name="Position" onKeyup="this.value=ignoreChar(this.value);">
</TD>
</TR>

</TABLE>