Solution : https://service.sap.com/sap/support/notes/335530 (SAP Service marketplace login required)
Key words : 
'system' -> 'status' displays patch level sapke40b00, directory general/r3server/abap/note, import hr legal change patches, additional key words lcp hr, system displays hr lcp level 53, continue importing subsequent hr lcps, intermediate status 'sapke40b00 = lcp00', ==> regular status 'sapke40b54 = lcp54', hr modifying add-ons, modified hr components maintained
Related Notes : 
       
| 556962 | FAQ OCS: General information on Support Packages | 
| 337428 | Pymts w/out cash disc.after Support Package 52 - 53 | 
| 334872 | Separation LCPs HR/Hot Packages in Release 4.0B |