nl_tokens: Read record summary at the begining of record section .
pl_tokens: function read_record_summary ( input , pos ) { var scanner = Scanner ( input ) , record_summary = { num_blocks : scanner . readNum ( ) , num_entries : scanner . readNum ( ) , index_len : scanner . readNum ( ) , blocks_len : scanner . readNum ( ) , // extra field len : scanner . <mask> ( ) , // actual length of record section (excluding record block index), varying with engine version attribute } ; // start position of record block from head of mdx/mdd file record_summary . block_pos = pos + record_summary . index_len + record_summary . len ; return record_summary ; }