First of all thank you Jürgen for the magnificent effort you put into documenting as well as coding GNU APL. In my experience trying to get coders to document their masterpieces is analogous to herding cats! But you have done an exemplary job of the highest quality. So I am just sending this as an FYI.
respect…. Peter Below is from GNUapl_1.8-1342 on which I have run Doxygen on the src and a few warnings have popped up in 2 files: ArrayIterator.cc:26: warning: documented symbol 'ArrayIteratorBase::ArrayIteratorBase' was not declared or defined. Prefix.cc:871: warning: documented symbol 'void Prefix::reduce____' was not declared or defined. Prefix.cc:880: warning: documented symbol 'void Prefix::reduce_LPAR_B_RPAR_' was not declared or defined. Prefix.cc:892: warning: documented symbol 'void Prefix::reduce_LPAR_F_C_RPAR' was not declared or defined. Prefix.cc:913: warning: documented symbol 'void Prefix::reduce_N___' was not declared or defined. Prefix.cc:931: warning: documented symbol 'void Prefix::reduce_MISC_F_B_' was not declared or defined. Prefix.cc:1083: warning: documented symbol 'void Prefix::reduce_MISC_F_C_B' was not declared or defined. Prefix.cc:1140: warning: documented symbol 'void Prefix::reduce_A_F_B_' was not declared or defined. Prefix.cc:1159: warning: documented symbol 'void Prefix::reduce_A_M_B_' was not declared or defined. Prefix.cc:1170: warning: documented symbol 'void Prefix::reduce_A_F_C_B' was not declared or defined. Prefix.cc:1193: warning: documented symbol 'void Prefix::reduce_A_M_C_B' was not declared or defined. Prefix.cc:1204: warning: documented symbol 'void Prefix::reduce_F_M__' was not declared or defined. Prefix.cc:1217: warning: documented symbol 'void Prefix::reduce_M_M__' was not declared or defined. Prefix.cc:1234: warning: documented symbol 'void Prefix::reduce_F_M_C_' was not declared or defined. Prefix.cc:1256: warning: documented symbol 'void Prefix::reduce_M_M_C_' was not declared or defined. Prefix.cc:1273: warning: documented symbol 'void Prefix::reduce_F_C_M_' was not declared or defined. Prefix.cc:1299: warning: documented symbol 'void Prefix::reduce_M_C_M_' was not declared or defined. Prefix.cc:1316: warning: documented symbol 'void Prefix::reduce_F_C_M_C' was not declared or defined. Prefix.cc:1350: warning: documented symbol 'void Prefix::reduce_M_C_M_C' was not declared or defined.