diff --git a/models/directdata/directdata.dat b/models/directdata/directdata.dat
index 119edbed..41d78ef5 100644
--- a/models/directdata/directdata.dat
+++ b/models/directdata/directdata.dat
@@ -184,8 +184,194 @@ d
 2048	422
 2049	446
 2050	470
+f[A1]
+1990	6100
+1991	6093.33
+1992	6086.67
+1993	6080
+1994	6073.33
+1995	6066.67
+1996	6060
+1997	6053.33
+1998	6046.67
+1999	6040
+2000	6033.33
+2001	6026.67
+2002	6020
+2003	6013.33
+2004	6006.67
+2005	6000
+2006	5990
+2007	5980
+2008	5970
+2009	5960
+2010	5950
+2011	5940
+2012	5930
+2013	5920
+2014	5910
+2015	5900
+2016	5902
+2017	5904
+2018	5906
+2019	5908
+2020	5910
+2021	5912
+2022	5914
+2023	5916
+2024	5918
+2025	5920
+2026	5922
+2027	5924
+2028	5926
+2029	5928
+2030	5930
+2031	5925
+2032	5920
+2033	5915
+2034	5910
+2035	5905
+2036	5900
+2037	5895
+2038	5890
+2039	5885
+2040	5880
+2041	5875
+2042	5870
+2043	5865
+2044	5860
+2045	5855
+2046	5850
+2047	5845
+2048	5840
+2049	5835
+2050	5830
+f[A2]
+1990	2100
+1991	2093.33
+1992	2086.67
+1993	2080
+1994	2073.33
+1995	2066.67
+1996	2060
+1997	2053.33
+1998	2046.67
+1999	2040
+2000	2033.33
+2001	2026.67
+2002	2020
+2003	2013.33
+2004	2006.67
+2005	2000
+2006	1990
+2007	1980
+2008	1970
+2009	1960
+2010	1950
+2011	1940
+2012	1930
+2013	1920
+2014	1910
+2015	1900
+2016	1896.67
+2017	1893.33
+2018	1890
+2019	1886.67
+2020	1883.33
+2021	1880
+2022	1876.67
+2023	1873.33
+2024	1870
+2025	1866.67
+2026	1863.33
+2027	1860
+2028	1856.67
+2029	1853.33
+2030	1850
+2031	1847.5
+2032	1845
+2033	1842.5
+2034	1840
+2035	1837.5
+2036	1835
+2037	1832.5
+2038	1830
+2039	1827.5
+2040	1825
+2041	1822.5
+2042	1820
+2043	1817.5
+2044	1815
+2045	1812.5
+2046	1810
+2047	1807.5
+2048	1805
+2049	1802.5
+2050	1800
 FINAL TIME
 1990	2050
+h
+1990	970
+1991	806
+1992	642
+1993	478
+1994	314
+1995	150
+1996	198
+1997	246
+1998	294
+1999	342
+2000	390
+2001	450
+2002	510
+2003	570
+2004	630
+2005	690
+2006	712
+2007	734
+2008	756
+2009	778
+2010	800
+2011	722
+2012	644
+2013	566
+2014	488
+2015	410
+2016	512
+2017	614
+2018	716
+2019	818
+2020	920
+2021	836
+2022	752
+2023	668
+2024	584
+2025	500
+2026	518
+2027	536
+2028	554
+2029	572
+2030	590
+2031	580
+2032	570
+2033	560
+2034	550
+2035	540
+2036	466
+2037	392
+2038	318
+2039	244
+2040	170
+2041	206
+2042	242
+2043	278
+2044	314
+2045	350
+2046	374
+2047	398
+2048	422
+2049	446
+2050	470
 INITIAL TIME
 1990	1990
 SAVEPER
@@ -278,3 +464,29 @@ c
 2040	17
 2045	35
 2050	47
+e[A1]
+1990	610
+2005	600
+2015	590
+2030	593
+2050	583
+e[A2]
+1990	210
+2005	200
+2015	190
+2030	185
+2050	180
+g
+1990	97
+1995	15
+2000	39
+2005	69
+2010	80
+2015	41
+2020	92
+2025	50
+2030	59
+2035	54
+2040	17
+2045	35
+2050	47
diff --git a/models/directdata/directdata.mdl b/models/directdata/directdata.mdl
index ba822284..10afb071 100644
--- a/models/directdata/directdata.mdl
+++ b/models/directdata/directdata.mdl
@@ -1,9 +1,17 @@
 {UTF-8}
-a[DimA] := GET DIRECT DATA('?data', 'A Data', 'A', 'B2') ~~|
 DimA: A1, A2 ~~|
-b[DimA] = a[DimA] * 10 ~~|
+
+a[DimA] := GET DIRECT DATA('?data', 'A Data', 'A', 'B2') ~~|
+b[DimA] = a[DimA] * 10 ~~~:SUPPLEMENTARY|
+
 c:= GET DIRECT DATA('?data', 'C Data', 'A', 'B2') ~~|
-d = c * 10 ~~|
+d = c * 10 ~~~:SUPPLEMENTARY|
+
+e[DimA] := GET DIRECT DATA('e_data.csv', ',', 'A', 'B2') ~~|
+f[DimA] = e[DimA] * 10 ~~~:SUPPLEMENTARY|
+
+g:= GET DIRECT DATA('g_data.csv', ',', 'A', 'B2') ~~|
+h = g * 10 ~~~:SUPPLEMENTARY|
 
 ********************************************************
 	.Control
diff --git a/models/directdata/e_data.csv b/models/directdata/e_data.csv
new file mode 100644
index 00000000..429ec617
--- /dev/null
+++ b/models/directdata/e_data.csv
@@ -0,0 +1,6 @@
+Year,A1,A2
+1990,610,210
+2005,600,200
+2015,590,190
+2030,593,185
+2050,583,180
\ No newline at end of file
diff --git a/models/directdata/g_data.csv b/models/directdata/g_data.csv
new file mode 100644
index 00000000..b8072144
--- /dev/null
+++ b/models/directdata/g_data.csv
@@ -0,0 +1,14 @@
+,g
+1990,97
+1995,15
+2000,39
+2005,69
+2010,80
+2015,41
+2020,92
+2025,50
+2030,59
+2035,54
+2040,17
+2045,35
+2050,47
\ No newline at end of file
diff --git a/src/CodeGen.js b/src/CodeGen.js
index 786b1fc4..a73ae0b5 100644
--- a/src/CodeGen.js
+++ b/src/CodeGen.js
@@ -19,7 +19,7 @@ export let codeGenerator = (parseTree, opts) => {
     outputAllVars = true
   }
   // Function to generate a section of the code
-  let generateSection = R.map(v => new EquationGen(v, extData, directData, mode).generate())
+  let generateSection = R.map(v => new EquationGen(v, extData, directData, mode, modelDirname).generate())
   let section = R.pipe(generateSection, R.flatten, lines)
   function generate() {
     // Read variables and subscript ranges from the model parse tree.
diff --git a/src/EquationGen.js b/src/EquationGen.js
index 83474b18..28683839 100644
--- a/src/EquationGen.js
+++ b/src/EquationGen.js
@@ -1,3 +1,4 @@
+import path from 'path'
 import R from 'ramda'
 import XLSX from 'xlsx'
 import { ModelLexer, ModelParser } from 'antlr4-vensim'
@@ -28,12 +29,13 @@ import {
   listConcat,
   newTmpVarName,
   permutationsOf,
+  readCsv,
   strToConst,
   vlog
 } from './Helpers.js'
 
 export default class EquationGen extends ModelReader {
-  constructor(variable, extData, directData, mode) {
+  constructor(variable, extData, directData, mode, modelDirname) {
     super()
     // the variable we are generating code for
     this.var = variable
@@ -43,6 +45,8 @@ export default class EquationGen extends ModelReader {
     this.directData = directData
     // set to 'decl', 'init-lookups', 'eval', etc depending on the section being generated
     this.mode = mode
+    // The model directory is required when reading data files for GET DIRECT DATA.
+    this.modelDirname = modelDirname
     // Maps of LHS subscript families to loop index vars for lookup on the RHS
     this.loopIndexVars = new LoopIndexVars(['i', 'j', 'k'])
     this.arrayIndexVars = new LoopIndexVars(['v', 'w'])
@@ -330,24 +334,42 @@ export default class EquationGen extends ModelReader {
     // If direct data exists for this variable, copy it from the workbook into one or more lookups.
     let result = []
     if (this.mode === 'init-lookups') {
-      let { tag, sheetName, timeRowOrCol, startCell } = this.var.directDataArgs
-      let workbook = this.directData.get(tag)
-      if (workbook) {
-        let sheet = workbook.Sheets[sheetName]
-        if (sheet) {
-          let indexNum = 0
-          if (!R.isEmpty(this.var.subscripts)) {
-            // Generate a lookup for a separated index in the variable's dimension.
-            // TODO allow the index to be in either position of a 2D subscript
-            let ind = sub(this.var.subscripts[0])
-            indexNum = ind.value
+      let getCellValue
+      let { file, tab, timeRowOrCol, startCell } = this.var.directDataArgs
+      if (file.startsWith('?')) {
+        // The file is a tag for an Excel file with data in the directData map.
+        let workbook = this.directData.get(file)
+        if (workbook) {
+          let sheet = workbook.Sheets[tab]
+          if (sheet) {
+            getCellValue = (c, r) => {
+              let cell = sheet[XLSX.utils.encode_cell({ c, r })]
+              return cell != null ? cdbl(cell.v) : null
+            }
+          } else {
+            throw new Error(`ERROR: Direct data worksheet ${tab} tagged ${file} not found`)
           }
-          result.push(this.generateDirectDataLookup(sheet, timeRowOrCol, startCell, indexNum))
         } else {
-          throw new Error(`ERROR: Direct data worksheet ${sheetName} tagged ${tag} not found`)
+          throw new Error(`ERROR: Direct data workbook tagged ${file} not found`)
         }
       } else {
-        throw new Error(`ERROR: Direct data workbook tagged ${tag} not found`)
+        // The file is a CSV pathname. Read it now.
+        let csvPathname = path.resolve(this.modelDirname, file)
+        let data = readCsv(csvPathname, tab)
+        if (data) {
+          getCellValue = (c, r) => (data[r] != null ? cdbl(data[r][c]) : null)
+        }
+      }
+      // If the data was found, convert it to a lookup.
+      if (getCellValue) {
+        let indexNum = 0
+        if (!R.isEmpty(this.var.subscripts)) {
+          // Generate a lookup for a separated index in the variable's dimension.
+          // TODO allow the index to be in either position of a 2D subscript
+          let ind = sub(this.var.subscripts[0])
+          indexNum = ind.value
+        }
+        result.push(this.generateDirectDataLookup(getCellValue, timeRowOrCol, startCell, indexNum))
       }
     }
     return result
@@ -368,7 +390,11 @@ export default class EquationGen extends ModelReader {
       if (mode === 'decl') {
         // In decl mode, declare a static data array that will be used to create the associated `Lookup`
         // at init time. See `generateLookup` for more details.
-        const points = R.reduce((a, p) => listConcat(a, `${cdbl(p[0])}, ${cdbl(p[1])}`, true), '', Array.from(data.entries()))
+        const points = R.reduce(
+          (a, p) => listConcat(a, `${cdbl(p[0])}, ${cdbl(p[1])}`, true),
+          '',
+          Array.from(data.entries())
+        )
         return `double ${dataName}[${data.size * 2}] = { ${points} };`
       } else if (mode === 'init-lookups') {
         // In init mode, create the `Lookup`, passing in a pointer to the static data array declared in decl mode.
@@ -444,13 +470,12 @@ export default class EquationGen extends ModelReader {
     }
     return result
   }
-
-  generateDirectDataLookup(sheet, timeRowOrCol, startCell, indexNum) {
+  generateDirectDataLookup(getCellValue, timeRowOrCol, startCell, indexNum) {
     // Read a row or column of data as (time, value) pairs from the worksheet.
-    let dataCol, dataRow, dataCell, timeCol, timeRow, timeCell, nextCell
+    // The cell(c,r) function wraps data access by column and row.
+    let dataCol, dataRow, dataValue, timeCol, timeRow, timeValue, nextCell
     let lookupData = ''
     let lookupSize = 0
-    let cell = (c, r) => sheet[XLSX.utils.encode_cell({ c, r })]
     let dataAddress = XLSX.utils.decode_cell(startCell)
     dataCol = dataAddress.c
     dataRow = dataAddress.r
@@ -473,14 +498,14 @@ export default class EquationGen extends ModelReader {
         timeCol++
       }
     }
-    timeCell = cell(timeCol, timeRow)
-    dataCell = cell(dataCol, dataRow)
-    while (timeCell && dataCell) {
-      lookupData = listConcat(lookupData, `${cdbl(timeCell.v)}, ${cdbl(dataCell.v)}`, true)
+    timeValue = getCellValue(timeCol, timeRow)
+    dataValue = getCellValue(dataCol, dataRow)
+    while (timeValue != null && dataValue != null) {
+      lookupData = listConcat(lookupData, `${timeValue}, ${dataValue}`, true)
       lookupSize++
       nextCell()
-      dataCell = cell(dataCol, dataRow)
-      timeCell = cell(timeCol, timeRow)
+      dataValue = getCellValue(dataCol, dataRow)
+      timeValue = getCellValue(timeCol, timeRow)
     }
     return [`  ${this.lhs} = __new_lookup(${lookupSize}, /*copy=*/true, (double[]){ ${lookupData} });`]
   }
@@ -725,7 +750,7 @@ export default class EquationGen extends ModelReader {
         // (since Vensim indices are one-based).
         let s = this.rhsSubscriptGen([varName])
         // Remove the brackets around the C subscript expression.
-        s = s.slice(1, s.length-1)
+        s = s.slice(1, s.length - 1)
         this.emit(`(${s} + 1)`)
       }
     } else {
diff --git a/src/EquationReader.js b/src/EquationReader.js
index 29dfc582..581234b5 100644
--- a/src/EquationReader.js
+++ b/src/EquationReader.js
@@ -127,13 +127,17 @@ export default class EquationReader extends ModelReader {
       this.expandDelayFunction(fn, args)
     } else if (fn === '_GET_DIRECT_DATA') {
       // Extract string constant arguments into an object used in code generation.
+      // For Excel files, the file argument names an indirect "?" file tag from the model settings.
+      // For CSV files, it gives a relative pathname in the model directory.
+      // For Excel files, the tab argument names an Excel worksheet.
+      // For CSV files, it gives the delimiter character.
       let args = R.map(
         arg => matchRegex(arg, /'(.*)'/),
         R.map(expr => expr.getText(), ctx.expr())
       )
       this.var.directDataArgs = {
-        tag: args[0],
-        sheetName: args[1],
+        file: args[0],
+        tab: args[1],
         timeRowOrCol: args[2],
         startCell: args[3]
       }
diff --git a/src/Helpers.js b/src/Helpers.js
index ca229fdd..af45b717 100644
--- a/src/Helpers.js
+++ b/src/Helpers.js
@@ -325,13 +325,8 @@ export let readCsv = (pathname, delimiter = ',') => {
     skip_empty_lines: true,
     skip_lines_with_empty_values: true
   }
-  try {
-    let data = B.read(pathname)
-    result = parseCsv(data, CSV_PARSE_OPTS)
-  } catch (error) {
-    console.error(`ERROR: CSV file ${pathname} not found`)
-  }
-  return result
+  let data = B.read(pathname)
+  return parseCsv(data, CSV_PARSE_OPTS)
 }
 // Convert the var name and subscript names to canonical form separately.
 export let canonicalVensimName = vname => {
diff --git a/src/SubscriptRangeReader.js b/src/SubscriptRangeReader.js
index dae67113..2d3f030f 100644
--- a/src/SubscriptRangeReader.js
+++ b/src/SubscriptRangeReader.js
@@ -109,11 +109,13 @@ export default class SubscriptRangeReader extends ModelReader {
     // Read subscript names from the CSV file at the given position.
     let csvPathname = path.resolve(this.modelDirname, pathname)
     let data = readCsv(csvPathname, delimiter)
-    let indexName = data[row][col]
-    while (indexName != null) {
-      this.indNames.push(indexName)
-      nextCell()
-      indexName = data[row] != null ? data[row][col] : null
+    if (data) {
+      let indexName = data[row][col]
+      while (indexName != null) {
+        this.indNames.push(indexName)
+        nextCell()
+        indexName = data[row] != null ? data[row][col] : null
+      }
     }
     super.visitExprList(ctx)
   }
diff --git a/src/sde-generate.js b/src/sde-generate.js
index 78fa4406..229ea966 100644
--- a/src/sde-generate.js
+++ b/src/sde-generate.js
@@ -107,12 +107,12 @@ export let generate = async (model, opts) => {
       extData = new Map([...extData, ...data])
     }
   }
-  // Attach Excel workbook data to directData entries by tag name.
+  // Attach Excel workbook data to directData entries by file name.
   let directData = new Map()
   if (spec.directData) {
-    for (let [tag, xlsxFilename] of Object.entries(spec.directData)) {
+    for (let [file, xlsxFilename] of Object.entries(spec.directData)) {
       let pathname = path.join(modelDirname, xlsxFilename)
-      directData.set(tag, readXlsx(pathname))
+      directData.set(file, readXlsx(pathname))
     }
   }
   // Produce a runnable model with the "genc" and "preprocess" options.