Short answer: GSO, OSO and SOP are terms used in Kazakhstan and Russia and differ by who approves them: the national register, an industry body or the company itself. CRM (certified reference material) is the international term for a certified material from a producer such as OREAS or Geostats.
GSO
A state reference material approved and entered in the national register. Used where metrological traceability to the national system is required.
OSO and SOP
An industry reference material (OSO) is approved at industry level. An enterprise reference material (SOP) is prepared and characterised by the organisation itself for internal QC.
CRM
A certified reference material from a specialist producer, characterised by inter-laboratory testing and supplied with a certificate of certified values and tolerances. OREAS produces materials under ISO 17034. Reporting under international codes such as JORC and NI 43-101 typically relies on CRMs for quality control.
Which to choose
Projects reporting under international codes or raising foreign capital use CRMs. See our reference material catalogue with live stock.