Native, inferred and semantic types

Tabalyst Scan records each field’s native types, infers a technical type from present values and chooses a primary interpretation only when one detector qualifies, then classifies the field in a family and a type (classification). Tabalyst Report calls the technical type the inferred type and displays the type of the classification in its Columns table.

Native source types

native_types in a Scan field counts values as read, before technical inference. CSV cells start as strings; JSON and Excel can carry typed values. The native type alone does not decide the inferred type.

Native type	Source value
string	Text, including text that may later parse as a number or date.
integer, number	A source number, with integer for whole numbers.
boolean	A source true/false value.
null	An explicit JSON null.
object, array	JSON containers; they can form paths or stay whole at a flatten limit.

See native_types and missing in the Scan field to distinguish source representation from missing-value rules.

Inferred types

The technical type is chosen from present values, after missing values are removed. Native scalar types contribute directly. Strings are classified with date, boolean and number rules. Tabalyst chooses the first family that reaches scan.types.minimum_confidence: integer, number (which also accepts integers), date, boolean, then text. Otherwise it chooses mixed. The report records type_counts, type_confidence and type_error_count; its Analysis settings gives the effective threshold.

Inferred type	When it appears	Important distinction
empty	No present analyzable value.	A missing-only field is not inferred as text.
complex	JSON objects or arrays kept whole at the configured flatten depth.	Their contents are not scalar columns at that depth.
boolean	Native booleans or technical true/false strings meet the threshold.	The separate boolean detector can recognize more configured word pairs.
integer	Whole-number values meet the threshold.	A leading-zero identifier stays text.
number	Numeric values, including integers and non-integers together, meet the threshold.	Configured decimal conventions decide which strings parse.
date	Calendar dates, including ambiguous day/month forms, meet the threshold.	Date-times and times can match the date detector without becoming calendar-date technical values.
text	Remaining text values meet the threshold.	Text can still have a semantic type such as email.
mixed	No family reaches the threshold.	No type error count is available because no type was accepted.

Error in the report counts present values outside the accepted inferred type. Missing values are excluded from its denominator. mixed reports the largest family as confidence but has no type error count.

Classification

Each field also has a family and a type, such as Identifier / Unique ID, Categorical / Enum, Contact / Email or Text / Short. They start from the technical type and the interpretations below, add the length of a text and the name of the column, and are described with their evidence in the Scan format. The Report refines an identifier with the exact distinct count of the second pass when it holds one.

Semantic types

Detectors become candidate interpretations when their matched share of eligible values reaches scan.detection.minimum_share. A field gets a primary interpretation only when exactly one detector qualifies. The classification reads every qualifying detector, not only the primary one. Technical number and boolean are not repeated as semantic types.

Semantic type	Meaning	Scope or condition
date	Date, date-time or time syntax.	A calendar-date inferred field is date; the date detector can also be primary for another field.
enumeration	A bounded set of recurring values.	Field-level rule: enough present values and no more than the configured distinct maximum.
email	Bare email address syntax.	Does not verify mailbox or domain ownership.
url	URL syntax and host.	Does not visit the URL or resolve its host.
phone	Supported phone syntax.	Does not check assigned numbers.
postal_code	Canadian or US postal-code syntax.	Does not check an assigned address.
currency	Number with currency symbol or code.	A bare number is not currency evidence.
percentage	Number followed by %.	The parsed value remains as written, such as 12 for 12%.
quantity	Number followed by a unit-shaped suffix.	Units are not validated as physical units.
uuid	UUID text form.	Does not verify that an ID was issued.
ip_address	IPv4 or IPv6 text form.	Does not check allocation or reachability.
pattern:<id>	Full-value match to a configured regular expression.	Exists only for a configured pattern.

Two qualifying detectors do not produce an arbitrary semantic type. Inspect all their evidence in Recognized patterns and in the report’s Detectors and formats table.

Measures by value family

Scan retains measures independently of its final technical type. For example, a mixed field can still have numeric evidence for the values that parsed as numbers. Report shows its Numeric analysis table only for inferred integer and number fields with usable statistics, and its String analysis table only for inferred text fields. The --details column page also exposes a bounded selection of Scan measures. Always check the measure’s population and status before comparing it with a column’s total rows.

All fields

Measure	Population and meaning	Where to read it
Present and missing	Values found at a field versus missing values or absent JSON members under a parent.	Scan presence and missing; Report Columns → Missing.
Distinct values	Different present analytical values after enabled Unicode composition, trim and whitespace collapse.	Scan values.cardinality and normalization stages; Report Columns → Distinct.
Frequencies and examples	Occurrence counts for listed values and a bounded sample of distinct values.	Scan values.frequencies and samples; Report Examples and its tooltip.
Type confidence and error	Share of present values in the accepted family and count outside it.	Scan technical_type; Report Inferred type and Error.
Variant groups	Raw spellings that share a final comparison key after enabled case and accent stages.	Scan normalization; Report Transformations.

Distinct counts and frequency lists can be limited; examples are a selection, not necessarily a complete distribution. A mixed field has no type error count because no family was accepted.

Numeric values

The Scan numeric block measures every accepted numeric value in the field, including native numbers and text parsed under the configured number rules. Its count, native_count and text_count identify this population. Report shows five summary measures for inferred numeric fields:

Measure	Definition	Availability
Minimum, Maximum	Smallest and largest accepted numeric value.	Scan and Report.
Range	Maximum minus minimum.	Derived in Report from the two bounds.
Mean	Sum divided by numeric count.	Scan and Report.
Median	Middle numeric value, averaging the two middle values when needed.	Scan measure; null in Report when its tracking limit was reached.
Sum	Total of accepted numeric values.	Scan and the standalone Report column page.
Population variance, standard deviation	Spread around the mean, using the numeric population.	Scan and the standalone Report column page.
Positive, negative, zero	Counts of numeric occurrences greater than, less than, or equal to zero. Missing and nonnumeric values are excluded.	Scan and the standalone Report column page.
Integral decimals	Decimal values whose numeric value is whole.	Scan and the standalone Report column page.

The numeric population can be smaller than the field’s present-value count if some values did not parse as numbers. In the Report table, Distinct and Examples describe normalized values, not the numeric calculation. When numeric statistics are complete, positive + negative + zero equals numeric.count. For example, 10, -2.5, 0, 4.5, and 1.0 yield 3 positive, 1 negative, and 1 zero value. A precision limit can make the numeric measure unavailable instead of showing partial sign counts.

Text values and lengths

Scan measures the length of each present analytical string after enabled Unicode composition, trim and internal whitespace collapse. Report’s string profile uses this measure only for an inferred text field.

Measure	Definition	Availability
Minimum, Maximum length	Shortest and longest observed analytical string, in characters.	Scan string_lengths; Report Min and Max, or Fixed if equal.
Mean, Median length	Average and middle character count, weighted by occurrences.	Scan and Report; Report leaves these cells blank when Fixed already gives the one length.
Fixed length	Minimum equals maximum; the shared length is displayed.	Derived in Report, not a claim about the field’s meaning.
Length distribution	Exact occurrence count for each observed length.	Scan histogram; Report Lengths only when the maximum fits string_analysis.length_distribution_max_length.
Distinct lengths	Number of different lengths observed.	Report JSON profile even when the HTML length distribution is omitted.
Length class	very_short, short, medium, long or very_long, chosen from the maximum length and the scan.classification bounds. The Text type of the Scan classification uses the same bounds on the median length.	Report Class.

Length examples come from bounded listed or sampled values. Distinct in the String analysis table counts values, not lengths. Scan also records string characteristics such as case, non-ASCII content, line breaks and whitespace.

Dates and times

The date detector separates unambiguous matches, ambiguous readings, invalid date-shaped values and other present values. Report’s Date analysis table appears when it finds date evidence, even if the field’s inferred type is not date.

Measure	Definition	Availability
Valid, ambiguous, invalid, other	Counts and percentages of eligible present values by outcome.	Report Date analysis and detector coverage in Scan.
Formats	Counts for each recognized format, including numeric orders, date-times and times.	Scan detector and Report Formats.
Ambiguity evidence	Unambiguous values per DMY and MDY order; evidence is shown but not applied to ambiguous values.	Scan detector details and Report date profile.
Temporal range	Minimum and maximum per kind: date, naive date-time, aware date-time or time. Aware and naive values are not compared together.	Scan temporal and the standalone Report column page.
Years	Count per year when applicable to a temporal kind.	Scan temporal and the standalone Report column page.

Only scan.detectors.date.ambiguous_order can explicitly resolve a supported ambiguous day/month order. Ambiguous values do not contribute to the temporal minimum and maximum.

Boolean values and other meanings

Scan booleans counts native and recognized technical true/false values separately as true and false; the standalone Report column page displays those counts. The configurable boolean detector can additionally recognize word pairs such as yes/no and oui/non; its matched counts and formats are detector evidence, not the same as the technical boolean counts.

For email, phone, postal_code, url, currency, percentage, quantity, uuid, ip_address, enumeration and configured patterns, the shared measures are detector coverage, format counts and bounded examples. Some detectors add details such as domains, hosts, units or UUID versions. Those details are in Recognized patterns and the Scan detector result; they do not imply external verification.

Limits and exposure

Scan wraps measures with a status: complete, limited, not_applicable, disabled or failed. A limited measure is never estimated; a lower bound, when present, is only a proven minimum. Sensitive fields can have numeric or temporal measures disabled under masking or hiding, while counts remain available. See measure envelopes and exposure settings.