How to apply "convert to metric/non-metric" in LO?

LO 4.4 US-en, Win7 64bit us.

I stubbled about a function in Tools>Options>Language Settings>English sentencing. There are under “Others” 2 functions to convert metric to non-metric and viseversa. The 3rd function to insert thousand periods/commas is clear.

I tried in Writer to enter 200lbs then Ctrl++, Paste Special and F2 Function. Nothing works. Help does not even mention this function, documentation explains how to set it but not how to use it.

Has sombody any idea how to apply this in a document

APPENDIX: I found the solution. There is a Lightproof Grammar checker installed (only english?) that has also the measurement convertion integrated. Important to enter a blank between number and unit (200 lbs NOT 200lbs). It takes a while until the blue wiggle line apears and then with right-click you can select your conversion. In the above example it shows 91 kg, 90.7 kg, 90.72 kg and 90.xxxxxxxxx kg.

This function was introduced with version 3.5.