WASHINGTON - The 2.1 percent of bank COBOL that GPT-6.1 Sol could not migrate, even at higher effort, has been granted protected heritage status by the Ministry of Financial Antiquities. The surviving routines sit on a fenced, roped-off partition of the mainframe. Engineers may view them but may not edit them. On 19 October OpenAI reported that GPT-6.1 Sol scored 86.6 percent on a COBOL migration test at low reasoning effort, up from 5.4 percent for GPT-5.6 Sol, and 97.9 percent at higher effort. OpenAI said COBOL still supports more than 40 percent of online banking systems and 95 percent of ATM transactions. MultiLangBench, on which GPT-6 Astra averaged 87.4 percent, lists COBOL, Fortran, and Visual Basic among low-resource languages. "The remaining 2.1 percent is irreplaceable," a ministry spokesperson said. "It is the last unmigrated core. A conservation permit is required before any character is altered." A plaque over one ATM balance-check routine is dated 1983. Flash photography of the source is banned. Visitors sign a logbook in the server room. The Mid-Atlantic Association of Clearing Banks issued Memo CAF-21 on conservation-permit procedure. A retired COBOL programmer has been hired as on-site custodian. Banks treat the designation as ordinary compliance. Inspections of the fenced partition take place on the first Monday of each month.