`REC::VertDoca` bank documentation mismatch for `cx*`, `cy*`, `cz*` fields

[skuditha]

There appears to be a mismatch between the documented meaning of several fields in the REC::VertDoca bank and what is actually written in the reconstruction code.

According to the bank definition in:
coatjava/etc/bankdefs/hipo4/even.json

the fields are described as direction vectors:

{"name":"cx1", "info":"x-direction vector of the first track at the DOCA point (cm)"},
{"name":"cy1", "info":"y-direction vector of the first track at the DOCA point (cm)"},
{"name":"cz1", "info":"z-direction vector of the first track at the DOCA point (cm)"},
...
{"name":"cx2", "info":"x-direction vector of the second track at the DOCA point (cm)"},
{"name":"cy2", "info":"y-direction vector of the second track at the DOCA point (cm)"},
{"name":"cz2", "info":"z-direction vector of the second track at the DOCA point (cm)"},

However, in the actual implementation (coatjava/reconstruction/vtx/src/main/java/org/jlab/rec/vtx/banks/Writer.java):

bank.setFloat("cx1", i, (float) vtx.get(i).getP1().getPx());
bank.setFloat("cy1", i, (float) vtx.get(i).getP1().getPy());
bank.setFloat("cz1", i, (float) vtx.get(i).getP1().getPz());

bank.setFloat("cx2", i, (float) vtx.get(i).getP2().getPx());
bank.setFloat("cy2", i, (float) vtx.get(i).getP2().getPy());
bank.setFloat("cz2", i, (float) vtx.get(i).getP2().getPz());

These area clearly momentum components (px, py, pz), not direction vectors.

Expected Behaviour

Either:

1. The documentation should reflect that these fields store momentum components (px, py, pz), or
2. The implementation should be updated to store normalized direction vectors if that was the original intent.

Impact

This discrepancy can lead to:

• Misinterpretation of the variables in analysis code
• Incorrect physics usage (e.g., assuming unit vectors when magnitudes are present)
• Potential downstream bugs in reconstruction or ML workflows