Why use CONNECT not PULL for low-value pull resistors? When a resistor is specified as a pull resistor the XJTAG system will expect two things:
First, it will expect one end of the resistor to be attached to a net that has been classified as a Power or Ground net.
Second, during the Connection Test it will expect to be able to drive the non-power/ground side of the resistor to the opposing value. So, if it is a pull-down resistor the connection test will check that it can drive the non-power side of the resistor high.
If you have a strong pull resistor, say 50 Ω, then it is not unusual that the JTAG device will be unable to supply enough current to oppose the pull resistor. In these cases where it is not intended for the pull of the resistor to be opposed, e.g. configuration strapping resistors, the resistor should be classified as a series resistor. The non-power net will still be covered by the connection test but instead of driving the net it will be checked that at no point does the net take the opposite value to its pulled value.
If a BOM is imported as part of the setup or if the net list contains the resistor values, e.g. the net list is in the RINF format, then the XJTAG system will not suggest low ohmic value resistors as pull resistors but instead will put them in the “Other Resistors” category so the user can assign them appropriately.