posixAccount entry differences in OpenLDAP 2.0.x and 2.1.x

[marc.bigler@day.com]

Hello,

Using OpenLDAP 2.0.x I used to enter such kind of entries:

dn: uid=test,ou=users,dc=domain,dc=tld
objectclass: posixAccount
cn: Test user
uid: test
uidNumber: 222
gidNumber: 222
homeDirectory: /home/test
userPassword: {SSHA}sshapassword

Now I am testing a new installation of OpenLDAP 2.1.17 and I simply cannot
enter this LDIF, ldapadd gives the following error:

ldapadd: update failed: dn: uid=test,ou=users,dc=domain,dc=tld
ldap_add: Object class violation (65)
        additional info: no structural object class provided

But now if I try using the following LDIF instead (I've simply added top
and account objectclass):

dn: uid=test,ou=users,dc=domain,dc=tld
objectclass: top
objectclass: account
objectclass: posixAccount
cn: Test user
uid: test
uidNumber: 222
gidNumber: 222
homeDirectory: /home/test
userPassword: {SSHA}sshapassword

Then it works fine, so I was wondering why with do I need to enter the
additional top and account objectclass since OpenLDAP 2.1.x ?

Regards
Marc