Official list of programs to be included in Linux?

The Linux Standard Base (LSB) has a list of applications:

[         du        install        mv            strings
ar        echo      install_initd  newgrp        strip
at        ed        ipcrm          nice          stty
awk       egrep     ipcs           nl            su
basename  env       join           nohup         sync
batch     expand    kill           od            tail
bc        expr      killall        passwd        tar
cat       false     ln             paste         tee
chfn      fgrep     locale         patch         test
chgrp     file      localedef      pathchk       tic
chmod     find      logger         pax           time
chown     fold      logname        pidof         touch
chsh      fuser     lp             pr            tput
cksum     gencat    lpr            printf        tr
cmp       getconf   ls             ps            true
col       gettext   lsb_release    pwd           tsort
comm      grep      m4             remove_initd  tty
cp        groupadd  mailx          renice        umount
cpio      groupdel  make           rm            uname
crontab   groupmod  man            rmdir         unexpand
csplit    groups    md5sum         sed           uniq
cut       gunzip    mkdir          sendmail      useradd
date      gzip      mkfifo         seq           userdel
dd        head      mknod          sh            usermod
df        hostname  mktemp         shutdown      wc
diff      iconv     more           sleep         xargs
dirname   id        mount          sort          zcat
dmesg     infocmp   msgfmt         split

Many of these are included as being part of the POSIX 1003.1-2001 standard, but the following are either only in LSB, or have differing specifications from POSIX:

ar       echo      hostname       more          sh
at       egrep     install        mount         shutdown
awk      fgrep     install_initd  msgfmt        su
batch    file      ipcrm          newgrp        sync
bc       fuser     ipcs           od            tar
chfn     gettext   killall        passwd        umount
chsh     grep      lpr            patch         useradd
col      groupadd  ls             pidof         userdel
cpio     groupdel  lsb_release    remove_initd  usermod
crontab  groupmod  m4             renice        xargs
df       groups    md5sum         sed           zcat
dmesg    gunzip    mknod          sendmail
du       gzip      mktemp         seq

The Wikipedia : list of Unix commands and Linuxconfig : Linux Commands are certainly worth a look.

However, many people tend to take a browse through at what's contained in the directories shown by echo $PATH and then look at the man page for more info.