• In Jainism, there isn’t a single fixed “caste” system like in some Hindu traditions. Surnames among Jains often reflect family lineage, regional origin, or trade, but they are not a doctrinal category of Jain dharma itself.

• Gadia as a surname: In contemporary Jain communities, you may encounter "Gadia" as a family name. It is used by some Jain families and can appear in lists of surnames within regional Jain groups. It is not a separate Jain caste unto itself, but rather a family/lineage name in certain communities. You may also see references to Gadia among groups that historically kept trade or gaddi (carriage) related names, but this does not imply a universal Jain identity separate from other Jain surnames.

• Vaniya (Banias) among Jains: Vaniya (also spelled Bania, Banija, Vania, etc.) is a mercantile community name that includes many Jain families. They are a socio-economic group rather than a strict Jain doctrinal category, and many Jain Vaniyas have historically engaged in trade, commerce, and business. Within Jainism, Vania is often treated as a community/gotra-like grouping rather than a spiritual lineage; practices can differ between Digambar and Shwetambar communities. You can read more on how Jain surnames and gotras are discussed in Jain community contexts.

• Gotra and lineage notes: In Jain tradition, the concept of gotra is not as rigid as in some Hindu lineages. Surnames and gotras in Jain communities are often region- or family-specific and may vary between Digambar and Shwetambar practices. For many families, the exact gotra mapping of a surname like Gadia or Verdia is a matter of local genealogical records and community custom rather than canonical Jain scriptures.

If you want, I can look for more specific Jain Knowledge pages that discuss Gadia or related surnames in particular communities (like Oswal, Bania, or Shwetambar/Digambar groups) and summarize their details.