Why is a chromatid, after anaphase, considered its own chromosome?

Hi!

See if this image helps...

So DNA supercoils to form chromatin and it becomes visible is that right? Then does that chromatin constitute one chromosome? Or does a chromosome only form when the DNA is duplicated?

Chromosome in cell about to enter meiosis: I

Duplicated DNA Chromosome (2 chromatids): ><

Metaphase 1 (lining up after crossing over, 2 homologulous chromosomes): >< ><

Anaphase 1 (two chromosomes): -----><         >< --------         (chromatids being pulled apart)

Anaphase 2 (4 chromatids splitting apart): ------>           < ---------
                                                 ------>           < ---------

Then do all chromatids become considered chromosomes or one un-duplicated set of DNA in a way

As in this photo:
https://upload.wikimedia.org/wikipedia/commons/thumb/5/54/Meiosis_diagram.jpg/1280px-Meiosis_diagram.jpg

Diploid cell = 4 straight lines (no x's)
Haploid cell = 2 straight lines (no x's)

The chromatin supercoils to become the chromosome you see in a karyotype. Think of an elastic band as chromatin. The more you twist it from both ends, it clumps. This clumped form is the supercoiled version we call a chromosome.