# Relationship history for MSHA mine 1510998

Current hierarchy: **Simpson William C → Black Diamond Processing Inc → Holt Tipple**

- Valid-time bounds: inclusive, date granularity
- Null end: open-ended in the upstream history row; not independent proof of present control
- Transaction-time observation: 2026-10-13T11:19:05.459773+00:00

## Valid-time edges

- **controller_controls_mine:** Ballard Tom → Holt Tipple; 1974-05-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Burchett Delbert → Holt Tipple; 1975-10-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Energy Development Corp → Holt Tipple; 1977-10-01 to 1978-08-31; source msha-controller-operator-history
- **controller_controls_operator:** Burchett Delbert → Energy Development Corp; 1977-10-01 to 1978-08-31; source msha-controller-operator-history
- **operator_operates_mine:** Tom Ballard Co Inc → Holt Tipple; 1978-09-01 to 1979-05-30; source msha-controller-operator-history
- **controller_controls_operator:** Ballard Tom → Tom Ballard Co Inc; 1978-09-01 to 1979-05-30; source msha-controller-operator-history
- **operator_operates_mine:** Black Diamond Processing Inc → Holt Tipple; 1979-05-31 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Simpson William C → Holt Tipple; 1979-05-31 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Simpson William C → Black Diamond Processing Inc; 1979-05-31 to current/open; source msha-controller-operator-history