Towards the end of the Birds series in the late 90s, the use of "X" in prefixes to indicate replacement notes was discontinued. Thus, identifiable (*, X) replacements ended and the current era of "unidentifiable" replacements began.
"Unidentifiable" replacement ranges are noted in catalogues, such as Charlton: "BC-54eA-i, Knight-Dodge, ANP (between 4.320M and 4.540M)."
How are these replacements determined? According to Charlton:
"It has been established that notes in certain number ranges have been inserted in new bricks of otherwise consecutively numbered notes, often from a different series.
"The information presented in this catalogue on "unidentifiable" replacement notes has not been, and may never be, confirmed from official sources. It has been obtained by reputable researchers from many regions of Canada, by searching bricks of new, untouched notes.
"The number ranges may change slightly as further discoveries are made with continuing research."
I wanted to ask how these would appear: as Macdonald $10s in bundles of Desmond $10s? Or as Wilkins-Poloz $5s in bundles of Wilkins-Macklem $5s? Or as FFG $10s in bundles of FFKs?
How big are these "bricks?" Some of these ranges are large, comprising hundreds of thousands of notes.
Also, I would imagine it would take time for these to be discovered, reported, verified, and then published. How long would it take for some of these replacements to appear in catalogues, a few years?