Dr. Ir. (Achmed) Soekarno, weaver

● All notes have a pair of different double Block letters (at lower left and upper right)

● The following combinations of Block letters are known:
AA PZ, AC PB, AG PF, AI UH, AL UK, AN UM, MB RA, MD RC, MF RE, MH RG, MK TI, MM TL, PP SO, and PW SV

● The 2nd and 4th Block letter
These letters have a fixed relationship, with the 2nd letter alphabetically one letter higher than the 4th letter.
(When the 2nd letter is an "A" then the 4th letter is a "Z".)
In order to prevent confusion, the letter "J" is omitted, and the combinations "JI" and "KJ" are not used, with "KI" substituted instead.
It is likely that the letter "Q" and the combinations "QP" and "RQ" are not used.
"RP" could have been used, but no notes are known with this combination.

This note has the Block letters MF RE.

Conclusion: It could be genuine.