Re: What value can cause this error?

Actually yes, I'm sure.
I have the errorInfo that shows the stack of procedure calls.
The procedure is called with "decimals" equal to 6.
The the error is thrown.
The errorInfo does not show the value of variable arguments, so I don't
know that "val" was.
I also checked my source code an all the calls to that procedure never
use higher values than 6 for the second argument.
Here is the complete procedure:
proc NumberReadmm {val {decimals 3}} {
  if {![string is double -strict $val]} {
    return $val
  }
  return [expr {round($val*(10.0**($decimals+3)))/(10.0**$decimals)}]mm
}
Here is the errorInfo:
*** ERROR ***
Time: Monday, das 16 von September, 2024, um 13:24:37
integer value too large to represent
    while executing
"expr {round($val*(10.0**($decimals+3)))/(10.0**$decimals)}"
    (procedure "NumberReadmm" line 5)
    invoked from within
"NumberReadmm $contact_offset 6"
    (procedure "ContactOffsetFormat" line 7)
    invoked from within
"ContactOffsetFormat $contact_offset_min"
    (procedure "UIRelationApplyContactOffset" line 45)
    invoked from within
"UIRelationApplyContactOffset %W"
    invoked from within
".valid.notebook.f5.buttons.b2 invoke "
    invoked from within
".valid.notebook.f5.buttons.b2 instate !disabled {
valid.notebook.f5.buttons.b2 invoke } "
    invoked from within
".valid.notebook.f5.buttons.b2 instate pressed {
valid.notebook.f5.buttons.b2 state !pressed;
valid.notebook.f5.buttons.b2 instate !disabled { .valid..."
    (command bound to event)