I just realized I've answered similar question myself earlier..
.NET API PdsType enumeration tells that 22 is type VOID.
Here's reference for anyone who might wonder the same thing:
PDS_NULL = 0,
PDS_I = 1,
PDS_PI = 2,
PDS_PPI = 3,
PDS_RGI = 4,
PDS_RGPI = 5,
PDS_CH = 6,
PDS_PCH = 7,
PDS_PPCH = 8,
PDS_RGCH = 9,
PDS_RGPCH = 10,
PDS_DUM_L = 11,
PDS_DUM_PL = 12,
PDS_DUM_PPL = 13,
PDS_DUM_RGL = 14,
PDS_DUM_RGPL = 15,
PDS_F = 16,
PDS_PF = 17,
PDS_PPF = 18,
PDS_RGF = 19,
PDS_RGPF = 20,
PDS_PDS = 21,
PDS_VOID = 22,
PDS_SEP = 23,
PDS_PPDS = 24,
PDS_CPCH = 25,
PDS_CPDS = 26,
PDS_INT64 = 27,
PDS_BOOL = 28,