Mistake: sub-ID truncated by a length limit

Mistake: sub-ID truncated by a length limit

Failure mode: you pack geo, creative, placement, and a hash into one sub-ID. The traffic source or network caps the field at 32 or 64 characters, silently truncates it, and your back-end postback can no longer match the click.

Fix — 4 steps:
— Find the documented max length for each sub-ID slot on your source and network. They differ. Assume nothing.
— Distribute data across multiple sub-ID slots (sub1 through sub5) instead of cramming one field.
— Keep the slot that carries your clickid short and clean — it is the matching key and must survive intact.
— Avoid characters that get URL-encoded (spaces, &, =) inside a sub-ID; they inflate length and break parsing.
— Use short codes mapped in a legend rather than full words: g=us, cr=12.

Verify: send a click with a maximal sub-ID, then check the value that arrives at the destination. It must be byte-for-byte intact.

Save this SOP. Run this before every launch.