Why some LUN's wwid shows 'p' as a last character to indicate partition number?

Issue

• Why some LUN's WWID shows p as a last character to indicate partition number but some wwid shows partition number without p?

• Why some PV shows the p after the lun's WWID while some don't?

# pvs
  PV                                              VG   Fmt  Attr PSize    PFree   
  /dev/mapper/360014050eba92db080747c099a380903p1      lvm2 ---  1023.00m 1023.00m    <---
  /dev/mapper/3600140533b05d2755d8448ea3a524ddf1       lvm2 ---  1023.00m 1023.00m    <---

• lsblk command shows that some of the WWID showing partition number after p but some WWID does not show p to show partition number.

# lsblk | egrep -i sdd\|sdb -A2
sdb                                       8:16   0    1G  0 disk  
├─sdb1                                    8:17   0 1023M  0 part  
└─36001405d89e5ff7af0b4cedaac8ecb92     253:4    0    1G  0 mpath 
  └─36001405d89e5ff7af0b4cedaac8ecb92p1 253:6    0 1023M  0 part    <---
--
sdd                                       8:48   0    1G  0 disk  
├─sdd1                                    8:49   0 1023M  0 part  
└─3600140533b05d2755d8448ea3a524ddf     253:2    0    1G  0 mpath 
  └─3600140533b05d2755d8448ea3a524ddf1  253:8    0 1023M  0 part    <---