Hello Victor,
Easiest way out is to ask read_char_value itself.
CALL METHOD cl_usmd_model_ext=>get_instance
EXPORTING
i_usmd_model = 'MM'
IMPORTING
eo_instance = lo_model_ext
et_message = et_message.
lo_model_ext->read_char_value(
EXPORTING
i_fieldname = if_mdg_gw_fiori_constants=>gc_usmd_crequest
it_sel = lt_sel " Pass the Crequest data in this select options table
i_readmode = if_usmd_model_ext=>gc_readmode_all_inact " Read mode
IMPORTING
et_data = lt_objlist
et_message = et_message
).
et_data will return the required material details locked in the CR supplied.
BR,
Avinash