Question is in the title. When I went through all defined primitive types, I got 0x01 through 0x22 (34) basically, but 0 and 0x0F (15) seem not defined.
The Recommendation ITU-T X.680 | ISO/IEC 8824-1 that specifies ASN.1 contains the following table (on page 14 in the PDF version):
| number | description |
|---|---|
| UNIVERSAL 0 | Reserved for use by the encoding rules |
| UNIVERSAL 1 | Boolean type |
| UNIVERSAL 2 | Integer type |
| UNIVERSAL 3 | Bitstring type |
| UNIVERSAL 4 | Octetstring type |
| UNIVERSAL 5 | Null type |
| UNIVERSAL 6 | Object identifier type |
| UNIVERSAL 7 | Object descriptor type |
| UNIVERSAL 8 | External type and Instance-of type |
| UNIVERSAL 9 | Real type |
| UNIVERSAL 10 | Enumerated type |
| UNIVERSAL 11 | Embedded-pdv type |
| UNIVERSAL 12 | UTF8String type |
| UNIVERSAL 13 | Relative object identifier type |
| UNIVERSAL 14 | The time type |
| UNIVERSAL 15 | Reserved for future editions of this Recommendation | International Standard |
| UNIVERSAL 16 | Sequence and Sequence-of types |
| UNIVERSAL 17 | Set and Set-of types |
| UNIVERSAL 18-22, 25-30 | Character string types |
| UNIVERSAL 23-24 | UTCTime and GeneralizedTime |
| UNIVERSAL 31-34 | DATE, TIME-OF-DAY, DATE-TIME and DURATION respectively |
| UNIVERSAL 35 | OID internationalized resource identifier type |
| UNIVERSAL 36 | Relative OID internationalized resource identifier type |
| UNIVERSAL 37-... | Reserved for addenda to this Recommendation | International Standard |
So 0x00, 0x0F and 0x25 and above are reserved, 0 for internal use and the others for "future editions" and "addenda". It is not clear what these future uses can be, but the position at exactly the 0xf border may point to some kind of memory/storage related uses.