First question...I have no idea. I use FM Pro 4.1 and I've never come across an error number -50. Try checking the help file under "Status (CurrentError) function.
Second question...In terms of HTML in general and the <form> tag in particular, by default, every element (<input>, <select>, etc.), except hidden ones, is part of a form's tab order. In most cases, the tabbing order of the elements matches the order of the elements within the <form> tag.
Theoretically, if you want to control the tab order, there is an attribute for form elements called tabindex which is part of HTML 4.0 standard. I'm not sure if any current browsers support this attribute. On a side note, Internet Explorer has introduced taborder and notab attributes which should work.
If you want to try these attributes, you will have to use Custom Web Publishing though.
Hope this helps!
[This message has been edited by chandra (edited August 16, 2000).]