Use a filed rate table

This guide reads the synthetic dwelling-fire table from Write your first rater. To follow along, save a copy of that rater and enter its folder:

rslc examples get dwelling
cd dwelling

WROTE dwelling/rater.rsl
WROTE dwelling/tables/BaseRate.csv

With a dwelling/ folder from the tutorial, run cd dwelling alone. The first excerpts quote rater.rsl in that folder.

Declare the table

Define the protection-class bands and perils in Types:

Peril = {
    fire,
    wind,
    theft
},
ProtectionClass = IntBands(1, 4, 7, 10..),

Declare BaseRate in Tables:

BaseRate [cite: manual:p3] :
    table dims (protection: ProtectionClass) -> {
        rate: Rate[Peril]
    }
    columns: {
        rate[fire]: "fire",
        rate[wind]: "wind",
        rate[theft]: "theft"
    }

dims defines the lookup key.
rate: Rate[Peril] returns one rate per peril.
columns maps those rates to CSV columns.
cite identifies the source location.

Save the CSV rows

The rows of BaseRate live in tables/BaseRate.csv:

protection,fire,wind,theft
1,2.10,0.80,0.40
4,2.60,0.80,0.45
7,3.40,0.85,0.50
10,5.20,0.90,0.60

Each protection value starts a band: 1–3, 4–6, 7–9, or 10 and above. Each key identifies one row. Keep numeric values as digits with a decimal point where needed.

Look up a rate

Pass the table name and key to lookup!, then select the returned value:

base_rate[p: Peril]: Rate =
    lookup!(BaseRate, self.dwelling.protection_class).rate[p],

For protection class 5, the lookup selects the row beginning at 4. Its fire rate is 2.60. The lookup has a name, base_rate, and the premium reads that name:

peril_premium[p: Peril]: Premium [cite: manual:p8] =
    round(self.dwelling.coverage_a / 1000 * self.base_rate[p], 2, half_up),

A lookup inside arithmetic gets its own name. Arithmetic over named values can nest, so the premium is one calculation. For Coverage A of 250,000, the fire premium is 250 × 2.60 = 650.

Tables with multiple keys

A table can use several key columns. The fn-tables example on the examples page keys its base rate by territory and construction:

BaseRate [cite: manual:p2] :
    table dims (territory: Territory, construction: Construction) -> {
        rate: Rate
    },

Its CSV contains one row per key combination:

territory,construction,rate
metro,frame,820
metro,masonry,740
suburban,frame,690
suburban,masonry,620
rural,frame,910
rural,masonry,830

Pass keys in declaration order:

base_rate: Rate = lookup!(BaseRate, self.territory, self.construction).rate

CSV headers with different names

Map RSL names to the CSV headers with columns. This small rater reads a ZIP table whose CSV has its own headers:

zip/rater.rsl

spec {
    rsl: "0.4.1",
    carrier: "Example Mutual",
    state: AZ,
    product: "Contents (filed ZIP rates)",
    effective_date: 2026-01-01
}

Sources = {
    manual: Source = {
        artifact: artifact("00000000-0000-4000-8000-000000000000"),
        kind: pdf
    }
}

Types = {
    Zip = Code(pattern: "[0-9]{5}")
}

Tables = {
    ZipRate [cite: manual:p15] :
        table dims (zip: Zip) -> {
            rate: Rate
        }
        columns: {
            zip: "zip_code",
            rate: "annual_rate"
        }
}

Records = {
    Policy = {
        inputs {
            zip: Key(ZipRate),
            contents: Num {precision: int} where self in [5000, 250000]
        },
        step premium {
            zip_rate: Rate = lookup!(ZipRate, self.zip).rate,
            premium: Premium [cite: manual:p16] = round(self.contents / 1000 * self.zip_rate, 0, half_up)
        }
    }
}

RatingOutcomes = {
    premium: Policy.premium
}

zip/tables/ZipRate.csv

zip_code,annual_rate
94110,100
94111,unfiled
94112,125.50

The columns block maps the key zip and the output rate to the two headers:

columns: {
    zip: "zip_code",
    rate: "annual_rate"
}

Read the rate an input selects

The subscript on a map column is a map binder, such as p, or one member, such as @Peril.fire. This small rater takes the peril as an input:

one-peril/rater.rsl

spec {
    rsl: "0.4.1",
    carrier: "Example Mutual",
    state: AZ,
    product: "Dwelling Fire (one peril)",
    effective_date: 2026-01-01
}

Sources = {
    manual: Source = {
        artifact: artifact("00000000-0000-4000-8000-000000000000"),
        kind: pdf
    }
}

Types = {
    Peril = {
        fire,
        wind,
        theft
    },
    ProtectionClass = IntBands(1, 4, 7, 10..),
    Money = Num {precision: 0.01}
}

Tables = {
    BaseRate [cite: manual:p3] :
        table dims (protection: ProtectionClass) -> {
            rate: Rate[Peril]
        }
        columns: {
            rate[fire]: "fire",
            rate[wind]: "wind",
            rate[theft]: "theft"
        }
}

Records = {
    Policy = {
        inputs {
            coverage_a: Money where self in [50000, 2000000],
            protection_class: Num {precision: int} where self in [1, 10],
            peril: Peril
        },
        step premium {
            base_rate[p: Peril]: Rate = lookup!(BaseRate, self.protection_class).rate[p],
            premium: Premium [cite: manual:p8] =
                round(self.coverage_a / 1000 * self.base_rate[self.peril], 0, half_up)
        }
    }
}

RatingOutcomes = {
    premium: Policy.premium
}

one-peril/tables/BaseRate.csv

protection,fire,wind,theft
1,2.10,0.80,0.40
4,2.60,0.80,0.45
7,3.40,0.85,0.50
10,5.20,0.90,0.60

To read the rate for the peril that the request names, read the column into a map and index that map with the input:

base_rate[p: Peril]: Rate = lookup!(BaseRate, self.protection_class).rate[p],
premium: Premium [cite: manual:p8] =
    round(self.coverage_a / 1000 * self.base_rate[self.peril], 0, half_up)

For protection class 5 and the peril wind, self.base_rate[self.peril] is 0.80. An input as the column’s own subscript, .rate[self.peril], gets E-MAP-DOMAIN.

Handle missing keys

Every lookup must find a value for each key it can receive. Choose the behavior supported by the filing:

Filing rule	Implementation
An “all other” rate applies	Add a cited `otherwise` value
Only listed keys are accepted	Restrict the input to filed keys
A business rule excludes certain keys	Add an input rule with its code and citation

An uncovered lookup fails rslc check with E-LOOKUP-GAP.

Use a filed fallback

Add otherwise when the filing provides an all-other value, as the fn-tables example does:

ZipFactor [cite: manual:p4] :
    table dims (zip: Zip) -> {
        factor: Factor
    }
    otherwise [cite: manual:p4]: { factor: 1 },

A ZIP absent from the CSV receives the factor 1. The fallback needs a citation to the filing’s all-other rule.

Accept only filed keys with Key(T)

For a table with one supported key column, Key(T) accepts values naming its filed rows.The zip rater under “CSV headers with different names” declares a five-digit ZIP type and a table:

Zip = Code(pattern: "[0-9]{5}")

ZipRate [cite: manual:p15] :
    table dims (zip: Zip) -> {
        rate: Rate
    }

Its input uses the table’s name in the input type:

zip: Key(ZipRate),

A missing key receives INPUT-KEY-UNFILED before rating. A wholly unfiled row also counts as missing.

Represent a blank filed rate

Use unfiled when the filing leaves an output blank. The zip rater’s CSV marks one row:

zip_code,annual_rate
94110,100
94111,unfiled
94112,125.50

A row whose outputs are all unfiled is treated as absent.Restrict accepted keys, or use a filing-supported otherwise value. A lookup that can reach an uncovered missing row produces E-LOOKUP-GAP.For a table with several output cells, a partly unfiled row produces E-TABLE-COL. Split outputs into separate tables when their filed rows differ.

Locate a point in a filed grid

Some plans key a table by a grid cell that the filing assigns from the risk’s latitude and longitude. Add each cell’s filed representative point to the table, and declare the grid as a geography.

grid/rater.rsl

spec {
    rsl: "0.4.1",
    carrier: "Example Mutual",
    state: AZ,
    product: "Homeowners Hail (projected grid)",
    effective_date: 2026-01-01
}

Sources = {
    manual: Source = {
        artifact: artifact("00000000-0000-4000-8000-000000000000"),
        kind: pdf
    }
}

Types = {
    GridId = Code(pattern: "G[0-9]{4}")
}

Constants = {
    base_premium [cite: manual:p2] = 900
}

Tables = {
    Grid [cite: manual:p547] :
        table dims (grid_id: GridId) -> {
            factor: Factor,
            latitude: Num {precision: 0.000001},
            longitude: Num {precision: 0.000001}
        }
}

Geographies = {
    TerritoryGrid [cite: manual:p547] = projected_grid {
        crs: esri_102008,
        cell: 200,
        origin_x: -2346800.383,
        origin_y: -1764199.182,
        cells: Grid,
        latitude: latitude,
        longitude: longitude,
        on_line: least_key
    }
}

Records = {
    Policy = {
        inputs {
            latitude: Num {precision: exact} where self in [-90, 90],
            longitude: Num {precision: exact} where self in [-180, 180]
        },
        step territory [cite: manual:p547] {
            grid_factor: Factor =
                match locate(TerritoryGrid, self.latitude, self.longitude) {
                    Some(g) => lookup!(Grid, g).factor,
                    None => 1.0
                }
        },
        step premium [cite: manual:p5] {
            premium: Premium [cite: manual:p5] = round(base_premium * self.grid_factor, 2, half_up)
        }
    }
}

RatingOutcomes = {
    premium: Policy.premium
}

grid/tables/Grid.csv

grid_id,factor,latitude,longitude
G0001,1.10,33.450000,-112.070000
G0002,1.25,33.460000,-112.080000

Tables = {
    Grid [cite: manual:p547] :
        table dims (grid_id: GridId) -> {
            factor: Factor,
            latitude: Num {precision: 0.000001},
            longitude: Num {precision: 0.000001}
        }
}

Geographies = {
    TerritoryGrid [cite: manual:p547] = projected_grid {
        crs: esri_102008,
        cell: 200,
        origin_x: -2346800.383,
        origin_y: -1764199.182,
        cells: Grid,
        latitude: latitude,
        longitude: longitude,
        on_line: least_key
    }
}

locate returns the key of the filed cell that holds the point, as an option:

grid_factor: Factor =
    match locate(TerritoryGrid, self.latitude, self.longitude) {
        Some(g) => lookup!(Grid, g).factor,
        None => 1.0
    }

A point on a line between cells takes the lesser code. Write the None arm as the filing directs: refuse the risk, remove the factor, or assign a filed code. A rater that uses locate rates on the native engine. When the filed cells are squares of latitude and longitude, declare a degree_grid. Its cell and origin are decimal degrees, as in the fn-geography example:

Geographies = {
    WildfireGrid [cite: manual:p3] = degree_grid {
        cell: 0.01,
        origin_latitude: 0,
        origin_longitude: 0,
        cells: WildfireCell,
        latitude: latitude,
        longitude: longitude,
        on_line: least_key
    }
}

locate(WildfireGrid, …) works as it does for a projected grid.

Check the rater

rslc check rater.rsl

PASS rater.rsl (strict)
cost premium: 16 + 2*|Policy.items| (each list of size 1: 18, 3: 22, 10: 36)

The check verifies lookup coverage for the inputs the rater accepts. Compare the extracted rates with the filing and test independent examples to verify their accuracy.

Next steps

Interpolate between table rows when the filing rates between two filed points.
Round a premium to apply the filing’s rounding rules.
Read the table messages to investigate table diagnostics.

Get started

Tutorials

Implement a filing

Test a rater

Quote and underwrite

Concepts

Reference

Use a filed rate table

Declare the table

Save the CSV rows

Look up a rate

Read the rate an input selects

Handle missing keys

Use a filed fallback

Locate a point in a filed grid

Check the rater

Next steps

​Declare the table

​Save the CSV rows

​Look up a rate

​Read the rate an input selects

​Handle missing keys

​Use a filed fallback

​Locate a point in a filed grid

​Check the rater

​Next steps

Declare the table

Save the CSV rows

Look up a rate

Read the rate an input selects

Handle missing keys

Use a filed fallback

Locate a point in a filed grid

Check the rater

Next steps