This article provides insight into the challenges of identifying religious affiliation in a medieval Arabic biographical text. It also offers guidance on useful questions and categorization methods. In the affiliation chart, the following elements should be recorded:

• Type of affiliation signal
• Signal strength (high, medium, or low)
• Affiliation description
• Affiliation: Choose Muslim, Christian, or Jewish. If no relevant information is available, mark as undesignated.

Key Types of Affiliation Signals

Five major types of affiliation signals can be identified:

1. Ancestor’s Name / Kunya

The affiliation of a paternal ancestor may be inferred through their name. Descent from a known Muslim dynasty or ruling family also provides a high-strength signal of Muslim affiliation.

2. Nisba

The nisba (attributive name) can explicitly reveal affiliation, such as:

• al-Naṣrānī (Christian)
• al-Isrāʾīlī (Jewish) These are typically high-strength signals.

3. Descendant’s Name

If a direct descendant is known and carries a clear affiliation signal, it is a high-strength indicator of the same affiliation for the ancestor—unless there is evidence of conversion.

4. Given Name

Certain given names are typically exclusive to a religious context. If such a name appears without counterindication, it counts as a high-strength signal:

• Islam: Muḥammad, Aḥmad, ʿAbd al-Raḥmān
• Christianity: Yūḥannā/Yuḥanna, Bukhtīshūʿ, Jibrāʾīl, Jūrjis/Jurjis/Jirjis, Mīkhāʾīl, Būluṣ, Isṭīfān, Mārī, Masīḥ, Mattā, Nasṭās, Sarjis, Tiyādūrus/Tayādūrus, Yūwānīs
• Judaism: Ḥasdāy, Ṣafiyya, Minaḥem

5. Occupation

Professions tied exclusively to a religion provide a high-strength signal of affiliation. Examples:

• Caliph, Islamic law scholar, Hadith transmitter → Muslim
• Catholicos → Christian

Some occupations imply but do not confirm affiliation (e.g., kalam philosopher), which may be considered a medium-strength signal unless further details are provided.

Other Signal Types

• Other description: Includes explicit statements of religious identity or conversion. Conversions dates or circumstances can be documented in the column "Affiliation Date". It should be also selected, if any further information gives plausible reason to suspect a certain affiliation (e.g. the ideological content of a cited poem). Depending on the level of detail and the plausibility of the description, the signal strength can be classified as high, medium, or low.
• Other relationship: Used when a family connection is mentioned but the exact nature (parent, descendant, sibling) is unclear.

Affiliation Description and Commentary

• Affiliation Description: Use this column to explain the specific details that indicate religious affiliation. Repeat the main content of the biographical entry if it directly relates to affiliation.
• Affiliation Comment: Provide any additional context, uncertainties, or challenges related to the affiliation. If referencing a translator's note, rephrase the content in your own words without quoting.

Sources

• If the information is directly from the IAU text, select IAU in the column "Affiliation source type" and provide the relevant chapter(s) in the format "X.X" in the column "Source IAU".
• If from a translator’s note or an external source (e.g., Encyclopedia of Islam, Wikipedia), specify the note in the format "X.Xn" or provide the link in the column "Source (external)".
• If a person’s affiliation is already clearly stated, no further research is required. In this case, mark the source type as "IAU-text or note" and provide the potential sources in the "Source IAU" column.

If external sources offer new or alternative information, a separate affiliation signal should be documented accordingly.