ACH processing is asynchronous. A successful create response means Slash
accepted the instruction; it does not mean the receiving bank settled it.
When a Transfer is scheduled, status is scheduled. Before network
submission, ach.submitsAt may identify the planned submission time. Once
processing begins, use the Transfer lifecycle rather than calculating a
settlement deadline from createdAt.
Banking days, network windows, reviews, approvals, and returns can all affect
timing. Do not promise availability based only on elapsed wall-clock time.
Rail fields such as companyEntryDescription,
companyDiscretionaryData, and addenda are sent to ACH processing. The API
rejects values longer than 10, 20, and 80 characters, respectively, before
creating the transfer, with 400 invalid_request. A value within those length
limits can still fail at submission if it violates another network rule.
