In the supplied Māṇḍūkya material, ukāra denotes the sound/letter 'u', identified as the second mātrā of oṃkāra in the decomposition of oṃkāra into its constituent sounds akāra–ukāra–makāra. The mūla correlates this mātrā with taijasa (the dream-state ātman) and glosses its name etymologically via utkarṣa ("exaltation/superiority") and ubhayatva ("being in between / partaking of both"). Gauḍapāda's kārikā restates the correlation, assigning ukāra the function of "leading/conveying" taijasa, parallel to akāra–viśva and makāra–prājña.
Senses
The reading surface. A later ingestion attaches a locus to a settled sense, or proposes a new one (dashed) for human triage — it never rewrites settled prose.
1 · The sound/letter 'u' as one of the three constituent mātrās of oṃkāra, listed second after…settledadded v1
The sound/letter 'u' as one of the three constituent mātrās of oṃkāra, listed second after akāra and before makāra.
upaniṣadic
mandukya.upanisad:8
2 · The second mātrā of oṃkāra correlated with taijasa (the dream-state ātman, svapnasthāna); …settledadded v1
The second mātrā of oṃkāra correlated with taijasa (the dream-state ātman, svapnasthāna); its name explained by utkarṣa (exaltation/being higher) and/or ubhayatva (being in between, partaking of both akāra and makāra). One who knows it thus exalts the continuity of knowledge, becomes equal/impartial, and has no non-knower-of-brahman in his lineage.
upaniṣadic
mandukya.upanisad:10mandukya.sankarabhasya:10
3 · In Gauḍapāda's verse, ukāra as that which 'leads/conveys' (nayate) taijasa, set in paralle…settledadded v1
In Gauḍapāda's verse, ukāra as that which 'leads/conveys' (nayate) taijasa, set in parallel with akāra→viśva and makāra→prājña.
advaita-vedānta
mandukya.karika:1.23
4 · In Śaṅkara's Āgamaśāstra-bhāṣya, the term ukāra does not occur as a phoneme/mātrā of oṃkār…proposedadded v2
In Śaṅkara's Āgamaśāstra-bhāṣya, the term ukāra does not occur as a phoneme/mātrā of oṃkāra but is incidental to commentary on dream/sleep states (viśva, taijasa, prājña), bondage, origination-and-dissolution, and upāsana of brahman — contexts not expressing ukāra as the 'u' sound of oṃkāra.
advaita-vedānta (Śaṅkara bhāṣya)
Why a new sense: These snippets concern taijasa/dream-sleep, bondage and non-arising, and upāsana — none thematize ukāra as the constituent sound of oṃkāra, so they do not fit the existing phoneme-centered senses.
Gauḍapāda: ukāra leads/conveys (nayate, governing the verse) taijasa, paralleling akāra→viśva and makāra→prājña; in the matra-less (amātra) there is no going/attainment. mandukya.karika:1.23
Attestation concordance — tier 2, every locus
Append-only. Grows by locus as texts arrive; stays one collapsed table so the senses remain the reading surface.
v1Māṇḍūkya mūla + Gauḍapāda kārikā — +3 loci 3 sense(s) drafted from 3 loci.
v2Śaṅkara bhāṣya — +4 loci · 1 routed to existing · 1 new sense(s) proposed Only mandukya.sankarabhasya:10 explicitly treats ukāra as the second mātrā of oṃkāra correlated with taijasa, explained via utkarṣa (utkṛṣṭa) and ubhayatva (madhyatva) — a verbatim match to s2's defining content. The three Āgamaśāstra-bhāṣya snippets (1.14 on viśva/taijasa and kārya-kāraṇa bondage; 2.32 on nirodha/utpatti-pralaya and the unreality of bondage; 3.1 on upāsana of aja brahman) do not mention ukāra as the 'u' sound or as a mātrā at all, so routing any of them to s1/s2/s3 would be unwarranted. They are grouped under one proposed sense flagging them as contexts that do not express the oṃkāra-phoneme meaning; if PramaKosha policy is to exclude non-attestations entirely, these may instead be dropped, but per the rule that every locus be accounted for, they are placed here.
Caveats
The supplied corpus is confined to the Māṇḍūkya tradition (mūla Upaniṣad plus Gauḍapāda's kārikā); no other textual traditions are represented in the evidence.
No Śaṅkara commentary locus was supplied, so no position is attributed to that witness.
The mūla's two etymologies for the name (utkarṣa and ubhayatva) are presented as alternatives ('-vā') within a single passage, not as a split between witnesses; the correlation ukāra↔taijasa is uniform across all supplied loci.