Hi Jain,
To be precise, it means that the postings you carry out with TPM1 at each key date are posted to certain OCI/equitty accounts based on Hedge Strategy you have used - Cash Flow or Fair Value and secondly based on the effective and ineffective portions. For Example in case of Cash Flow Hedge the Changes to fair value of the Hedging instrument that is effective are posted to Equity account and the ineffective portion is realized to PnL immediately. Towards the Maturity when the HR is dissolved or De-designated, the effective portions are reclassified to PnL. The OCI balance is then treated as Earning.
Also THM50 is indeed for transferring Ineffective portion. As its a Prospective Assessment transaction, when you execute it, it will show you the desired HRs which are effective(indicated as Green Light). But when you double click the green light, the light turns red which means that the HR is marked as ineffective. Hence on saving on this status the HR is either De-designated or Dissolved based on the settings you made in customizing.
Regards,
Nikhil