Osmocom C files syntax understanding

Dear baseband-developers team,      Would you be so kind to advise me on the following:   I desire (dramatically want very much) to learn / understand Osmocom projects. I am a beginner in programming and i try to understand / learn C files that the project is build of.   As an example i tried to learn / understand for example an Osmocom message buffer — msgb.h file.   But immediately faced some syntax difficulties:   This is the extract of msgb.h file:   struct msgb {     struct llist_head list; /*!< \brief linked list header */     /* Part of which TRX logical channel we were received / transmitted */     /* FIXME: move them into the control buffer */     union {         void *dst; /*!< \brief reference of origin/destination */          struct gsm_bts_trx *trx;     };   As it can be seen a structure «msgb» has as one of its components another structure — «gsm_bts_trx»   But in whole Osmocom BB project files i could not find definition / description of struct «gsm_bts_trx».   Would you kindly advise me please how to see which components / constituents / elements are in this gsm_bts_trx structure? From which components is struct gsm_bts_trx build of?   Thank you so much for your kind advise.   -- Mario Lucas