Understanding Public Id using "1.x"

There are a few public Ids that contain the version as “1.x” ( say - PUBLIC "-//OASIS//DTD DITA 1.x Concept//EN" "concept.dtd").

  I am a little confused with this.
Does this mean that the public Id will contain “1.x”

  OR

  it means match public Ids containing all sub-versions of version 1.0 i.e. it matches

  - "-//OASIS//DTD DITA 1.0 Concept//EN" "concept.dtd

  - "-//OASIS//DTD DITA 1.1 Concept//EN" "concept.dtd

  - "-//OASIS//DTD DITA 1.2 Concept//EN" "concept.dtd

  Regards,

  Tarun Garg | Adobe Systems | +91-120-2444711 |