diff --git a/.github/workflows/go.yml b/.github/workflows/go.yml
index 204c2de..efd3443 100644
--- a/.github/workflows/go.yml
+++ b/.github/workflows/go.yml
@@ -19,7 +19,7 @@ jobs:
     - name: Set up Go
       uses: actions/setup-go@v4
       with:
-        go-version: '1.20'
+        go-version: '1.21'
 
     - name: Install dependencies
       run: go get .
diff --git a/convert/config.go b/convert/config.go
index 7d3ca0c..763762f 100644
--- a/convert/config.go
+++ b/convert/config.go
@@ -1,7 +1,6 @@
 package bedgovcf
 
 import (
-	"fmt"
 	"log"
 	"os"
 	"strings"
@@ -28,62 +27,55 @@ func ReadConfig(configString string) Config {
 
 // Validate the config
 func (c *Config) validate() {
-	if c.Chrom.Field == "" {
-		log.Printf("No field defined for CHROM, defaulting to the column 0")
-		c.Chrom.Field = "0"
+	if c.Chrom.Value == "" {
+		log.Printf("No value defined for CHROM, defaulting to the column 0")
+		c.Chrom.Value = "$0"
 	}
 
-	if c.Pos.Field == "" {
-		log.Printf("No field defined for POS, defaulting to the column 1")
-		c.Pos.Field = "1"
+	if c.Pos.Value == "" {
+		log.Printf("No value defined for POS, defaulting to the column 1")
+		c.Pos.Value = "$1"
 	}
 
-	if c.Id.Field == "" && c.Id.Prefix == "" {
-		log.Printf("No field or prefix specified for the ID, defaulting to prefix 'id_")
+	if c.Id.Value == "" && c.Id.Prefix == "" {
+		log.Printf("No value or prefix specified for the ID, defaulting to prefix 'id_")
 		c.Id.Prefix = "id_"
 	}
 
-	if c.Ref.Field == "" && c.Ref.Value == "" {
-		log.Printf("No field or value specified for the REF, defaulting to value 'N")
+	if c.Ref.Value == "" {
+		log.Printf("No value specified for the REF, defaulting to value 'N")
 		c.Ref.Value = "N"
 	}
 
-	if c.Alt.Field == "" && c.Alt.Value == "" {
-		log.Printf("No field or value specified for the ALT, defaulting to value '<CNV>")
+	if c.Alt.Value == "" {
+		log.Printf("No value specified for the ALT, defaulting to value '<CNV>")
 		c.Alt.Value = "<CNV>"
 	}
 
-	if c.Qual.Field == "" && c.Qual.Value == "" {
-		log.Printf("No field or value specified for the QUAL, defaulting to value '.'")
+	if c.Qual.Value == "" {
+		log.Printf("No value specified for the QUAL, defaulting to value '.'")
 		c.Qual.Value = "."
 	}
 
-	if c.Filter.Field == "" && c.Filter.Value == "" {
-		log.Printf("No field or value specified for the FILTER, defaulting to value 'PASS'")
+	if c.Filter.Value == "" {
+		log.Printf("No value specified for the FILTER, defaulting to value 'PASS'")
 		c.Filter.Value = "PASS"
 	}
 
-	errStrings := []string{}
-
 	if len(c.Info) != 0 {
 		for k, v := range c.Info {
-			if v.Field == "" && v.Value == "" {
-				s := fmt.Sprintf("No field or value specified for the INFO/%v", strings.ToUpper(k))
-				errStrings = append(errStrings, s)
+			if v.Value == "" {
+				log.Printf("No value specified for the INFO/%v", strings.ToUpper(k))
 			}
 		}
 	}
 
 	if len(c.Format) != 0 {
 		for k, v := range c.Format {
-			if v.Field == "" && v.Value == "" {
-				s := fmt.Sprintf("No field or value specified for the FORMAT/%v", strings.ToUpper(k))
-				errStrings = append(errStrings, s)
+			if v.Value == "" {
+				log.Printf("No value specified for the FORMAT/%v", strings.ToUpper(k))
 			}
 		}
 	}
 
-	if len(errStrings) != 0 {
-		log.Fatalf("The following errors were found in the config file:\n%v", strings.Join(errStrings, "\n"))
-	}
 }
diff --git a/convert/resolve.go b/convert/resolve.go
new file mode 100644
index 0000000..f647819
--- /dev/null
+++ b/convert/resolve.go
@@ -0,0 +1,143 @@
+package bedgovcf
+
+import (
+	"fmt"
+	"log"
+	"math"
+	"slices"
+	"strconv"
+	"strings"
+)
+
+func resolveField(configValues []string, bedValues []string, bedHeader []string) string {
+
+	input := []string{}
+	for _, v := range configValues {
+		if strings.HasPrefix(v, "$") {
+			var headerIndex int
+			for j, w := range bedHeader {
+				if w == v[1:] {
+					headerIndex = j
+					break
+				}
+			}
+			input = append(input, bedValues[headerIndex])
+			continue
+		} else {
+			input = append(input, v)
+		}
+	}
+
+	function := ""
+	if strings.HasPrefix(input[0], "~") {
+		function = configValues[0][1:]
+	} else {
+		return strings.Join(input, " ")
+	}
+
+	switch function {
+	case "round":
+		// ~round <value>
+		float, err := strconv.ParseFloat(input[1], 64)
+		if err != nil {
+			log.Fatalf("Failed to parse the value (%v) to a float: %v", input[1], err)
+		}
+		round := math.Round(float)
+		if round == -0 {
+			round = 0
+		}
+		return fmt.Sprintf("%v", round)
+	case "sum":
+		// ~sum <value1> <value2> ...
+		var sum float64
+		for _, v := range input[1:] {
+			float, err := strconv.ParseFloat(v, 64)
+			if err != nil {
+				log.Fatalf("Failed to parse the value (%v) to a float: %v", v, err)
+			}
+			sum += float
+		}
+
+		return strconv.FormatFloat(sum, 'g', -1, 64)
+	case "min":
+		// ~min <startValue> <valueToSubstract1> <valueToSubstract2> ...
+		min, err := strconv.ParseFloat(input[1], 64)
+		if err != nil {
+			log.Fatalf("Failed to parse the value (%v) to a float: %v", input[1], err)
+		}
+		for _, v := range input[2:] {
+			float, err := strconv.ParseFloat(v, 64)
+			if err != nil {
+				log.Fatalf("Failed to parse the value (%v) to a float: %v", v, err)
+			}
+			min -= float
+		}
+		return strconv.FormatFloat(min, 'g', -1, 64)
+	case "if":
+		// ~if <value1> <operator> <value2> <value_if_true> <value_if_false>
+		// supported operators: > < >= <= ==
+		v1 := input[1]
+		operator := input[2]
+		v2 := input[3]
+		vTrue := input[4]
+		vFalse := input[5:]
+
+		floatV1, err1 := strconv.ParseFloat(v1, 64)
+		floatV2, err2 := strconv.ParseFloat(v2, 64)
+
+		floatOperators := []string{"<", ">", "<=", ">="}
+		if slices.Contains(floatOperators, operator) && (err1 != nil || err2 != nil) {
+			log.Fatalf("Failed to parse the values (%v and %v) to a float: %v and %v", v1, v2, err1, err2)
+		}
+
+		vFalseResolved := ""
+		if strings.HasPrefix(vFalse[0], "~") {
+			vFalseResolved = resolveField(vFalse, bedValues, bedHeader)
+		} else {
+			vFalseResolved = strings.Join(vFalse, " ")
+		}
+
+		switch operator {
+		case "<":
+			if floatV1 < floatV2 {
+				return vTrue
+			} else {
+				return vFalseResolved
+			}
+		case ">":
+			if floatV1 > floatV2 {
+				return vTrue
+			} else {
+				return vFalseResolved
+			}
+		case ">=":
+			if floatV1 >= floatV2 {
+				return vTrue
+			} else {
+				return vFalseResolved
+			}
+		case "<=":
+			if floatV1 <= floatV2 {
+				return vTrue
+			} else {
+				return vFalseResolved
+			}
+		case "==":
+			if err1 == nil && err2 == nil {
+				if floatV1 == floatV2 {
+					return vTrue
+				} else {
+					return vFalseResolved
+				}
+			} else {
+				if v1 == v2 {
+					return vTrue
+				} else {
+					return vFalseResolved
+				}
+			}
+		}
+	}
+
+	return ""
+}
diff --git a/convert/resolve_test.go b/convert/resolve_test.go
new file mode 100644
index 0000000..5300733
--- /dev/null
+++ b/convert/resolve_test.go
@@ -0,0 +1,158 @@
+package bedgovcf
+
+import "testing"
+
+func TestFieldResolving(t *testing.T) {
+	value := resolveField([]string{"$test"}, []string{"value"}, []string{"test"})
+	if value != "value" {
+		t.Fatalf("Expected value to be 'value', got %s", value)
+	}
+
+	value = resolveField([]string{"$test", "$test2"}, []string{"value", "I don't want this", "value2"}, []string{"test", "whut", "test2"})
+	if value != "value value2" {
+		t.Fatalf("Expected value to be 'value value2', got %s", value)
+	}
+
+	value = resolveField([]string{"~sum", "$test", "$test2"}, []string{"10", "I don't want this", "2"}, []string{"test", "whut", "test2"})
+	if value != "12" {
+		t.Fatalf("Expected value to be '12', got %s", value)
+	}
+}
+
+func TestRound(t *testing.T) {
+	value := resolveField([]string{"~round", "1.5"}, []string{}, []string{})
+	if value != "2" {
+		t.Fatalf("Expected value to be '2', got %s", value)
+	}
+
+	value = resolveField([]string{"~round", "1.4"}, []string{}, []string{})
+	if value != "1" {
+		t.Fatalf("Expected value to be '1', got %s", value)
+	}
+
+	value = resolveField([]string{"~round", "-2.3"}, []string{}, []string{})
+	if value != "-2" {
+		t.Fatalf("Expected value to be '-2', got %s", value)
+	}
+
+	value = resolveField([]string{"~round", "-0.2"}, []string{}, []string{})
+	if value != "0" {
+		t.Fatalf("Expected value to be '0', got %s", value)
+	}
+}
+
+func TestSum(t *testing.T) {
+	value := resolveField([]string{"~sum", "1.5"}, []string{}, []string{})
+	if value != "1.5" {
+		t.Fatalf("Expected value to be '1.5', got %s", value)
+	}
+
+	value = resolveField([]string{"~sum", "1", "2"}, []string{}, []string{})
+	if value != "3" {
+		t.Fatalf("Expected value to be '3', got %s", value)
+	}
+
+	value = resolveField([]string{"~sum", "-2", "2"}, []string{}, []string{})
+	if value != "0" {
+		t.Fatalf("Expected value to be '0', got %s", value)
+	}
+
+	value = resolveField([]string{"~sum", "10", "15", "20", "-5"}, []string{}, []string{})
+	if value != "40" {
+		t.Fatalf("Expected value to be '40', got %s", value)
+	}
+
+	value = resolveField([]string{"~sum", "-10", "-20", "5"}, []string{}, []string{})
+	if value != "-25" {
+		t.Fatalf("Expected value to be '-25', got %s", value)
+	}
+}
+
+func TestMin(t *testing.T) {
+	value := resolveField([]string{"~min", "1.5"}, []string{}, []string{})
+	if value != "1.5" {
+		t.Fatalf("Expected value to be '1.5', got %s", value)
+	}
+
+	value = resolveField([]string{"~min", "1", "2"}, []string{}, []string{})
+	if value != "-1" {
+		t.Fatalf("Expected value to be '-1', got %s", value)
+	}
+
+	value = resolveField([]string{"~min", "-2", "2"}, []string{}, []string{})
+	if value != "-4" {
+		t.Fatalf("Expected value to be '-4', got %s", value)
+	}
+
+	value = resolveField([]string{"~min", "50", "15", "20", "-5"}, []string{}, []string{})
+	if value != "20" {
+		t.Fatalf("Expected value to be '20', got %s", value)
+	}
+
+	value = resolveField([]string{"~min", "-10", "-20", "5"}, []string{}, []string{})
+	if value != "5" {
+		t.Fatalf("Expected value to be '5', got %s", value)
+	}
+}
+
+func TestIf(t *testing.T) {
+	value := resolveField([]string{"~if", "1", ">", "2", "true", "false"}, []string{}, []string{})
+	if value != "false" {
+		t.Fatalf("Expected value to be 'false', got %s", value)
+	}
+
+	value = resolveField([]string{"~if", "1", "<", "2", "true", "false"}, []string{}, []string{})
+	if value != "true" {
+		t.Fatalf("Expected value to be 'true', got %s", value)
+	}
+
+	value = resolveField([]string{"~if", "1", "<=", "2", "true", "false"}, []string{}, []string{})
+	if value != "true" {
+		t.Fatalf("Expected value to be 'true', got %s", value)
+	}
+
+	value = resolveField([]string{"~if", "2", "<=", "2", "true", "false"}, []string{}, []string{})
+	if value != "true" {
+		t.Fatalf("Expected value to be 'true', got %s", value)
+	}
+
+	value = resolveField([]string{"~if", "1", ">=", "2", "true", "false"}, []string{}, []string{})
+	if value != "false" {
+		t.Fatalf("Expected value to be 'false', got %s", value)
+	}
+
+	value = resolveField([]string{"~if", "2", ">=", "2", "true", "false"}, []string{}, []string{})
+	if value != "true" {
+		t.Fatalf("Expected value to be 'true', got %s", value)
+	}
+
+	value = resolveField([]string{"~if", "1", "==", "2", "true", "false"}, []string{}, []string{})
+	if value != "false" {
+		t.Fatalf("Expected value to be 'false', got %s", value)
+	}
+
+	value = resolveField([]string{"~if", "1", "==", "1", "true", "false"}, []string{}, []string{})
+	if value != "true" {
+		t.Fatalf("Expected value to be 'true', got %s", value)
+	}
+
+	value = resolveField([]string{"~if", "test", "==", "test2", "true", "false"}, []string{}, []string{})
+	if value != "false" {
+		t.Fatalf("Expected value to be 'false', got %s", value)
+	}
+
+	value = resolveField([]string{"~if", "test", "==", "test", "true", "false"}, []string{}, []string{})
+	if value != "true" {
+		t.Fatalf("Expected value to be 'true', got %s", value)
+	}
+
+	value = resolveField([]string{"~if", "test", "==", "test2", "true", "~sum", "10", "20"}, []string{}, []string{})
+	if value != "30" {
+		t.Fatalf("Expected value to be '30', got %s", value)
+	}
+
+	value = resolveField([]string{"~if", "test", "==", "test", "true", "~sum", "10", "20"}, []string{}, []string{})
+	if value != "true" {
+		t.Fatalf("Expected value to be 'true', got %s", value)
+	}
+}
diff --git a/convert/structs.go b/convert/structs.go
index 4e22411..9e7288e 100644
--- a/convert/structs.go
+++ b/convert/structs.go
@@ -27,7 +27,6 @@ type ConfigHeaderStruct struct {
 
 // The struct for the standard fields
 type ConfigStandardFieldStruct struct {
-	Field   string               // The field to use as value
 	Value   string               // The value to use
 	Prefix  string               // The prefix to add to each value
 	Options []ConfigHeaderStruct // The different options possible (only for ALT and FILTER)
@@ -38,7 +37,6 @@ type MapConfigInfoFormatStruct map[string]ConfigInfoFormatStruct
 
 // The struct for the info and format fields
 type ConfigInfoFormatStruct struct {
-	Field       string // The field to use as value
 	Value       string // The value to use
 	Prefix      string // The prefix to add to each value
 	Description string // The description of the field
diff --git a/convert/vcf.go b/convert/vcf.go
index ee9726b..43ea5a4 100644
--- a/convert/vcf.go
+++ b/convert/vcf.go
@@ -190,20 +190,8 @@ func (cifs *ConfigInfoFormatStruct) getValue(values []string, header []string) s
 		prefix = cifs.Prefix
 	}
 
-	// TODO write a resolve function for conditional fields
-	if cifs.Field != "" {
-		var headerIndex int
-		for i, v := range header {
-			if v == cifs.Field {
-				headerIndex = i
-				break
-			}
-		}
-		return prefix + values[headerIndex]
-	} else if cifs.Value != "" {
-		return prefix + cifs.Value
-	}
-	return ""
+	return prefix + resolveField(strings.Split(cifs.Value, " "), values, header)
+
 }
 
 // Get the value for the given field based on the config
@@ -213,20 +201,8 @@ func (csfs *ConfigStandardFieldStruct) getValue(values []string, header []string
 		prefix = csfs.Prefix
 	}
 
-	// TODO write a resolve function for conditional fields
-	if csfs.Field != "" {
-		var headerIndex int
-		for i, v := range header {
-			if v == csfs.Field {
-				headerIndex = i
-				break
-			}
-		}
-		return prefix + values[headerIndex]
-	} else if csfs.Value != "" {
-		return prefix + csfs.Value
-	}
-	return ""
+	return prefix + resolveField(strings.Split(csfs.Value, " "), values, header)
+
 }
 
 // Write the VCF struct to stdout or a file
@@ -238,8 +214,8 @@ func (v *Vcf) Write(cCtx *cli.Context) {
 
 	if stdout {
 		fmt.Print(v.Header.String())
-		for _, variant := range v.Variants {
-			fmt.Print(variant.String())
+		for count, variant := range v.Variants {
+			fmt.Print(variant.String(count))
 		}
 	} else {
 		file, err := os.Create(cCtx.String("output"))
@@ -248,19 +224,21 @@ func (v *Vcf) Write(cCtx *cli.Context) {
 		}
 		defer file.Close()
 		file.WriteString(v.Header.String())
-		for _, variant := range v.Variants {
-			file.WriteString(variant.String())
+		for count, variant := range v.Variants {
+			file.WriteString(variant.String(count))
 		}
 	}
 }
 
 // Convert a variant to a string
-func (v Variant) String() string {
+func (v Variant) String(count int) string {
+
+	id := fmt.Sprintf("%v%v", v.Id, count)
 
 	variant := strings.Join([]string{
 		v.Chrom,
 		v.Pos,
-		v.Id,
+		id,
 		v.Ref,
 		v.Alt,
 		v.Qual,
diff --git a/convert/vcf_test.go b/convert/vcf_test.go
index a3363b2..c1003da 100644
--- a/convert/vcf_test.go
+++ b/convert/vcf_test.go
@@ -56,7 +56,7 @@ func TestSetHeaderLines(t *testing.T) {
 			},
 		},
 		Alt: ConfigStandardFieldStruct{
-			Field: "test",
+			Value: "$test",
 			Options: []ConfigHeaderStruct{
 				{
 					Name:        "DUP",
@@ -65,7 +65,7 @@ func TestSetHeaderLines(t *testing.T) {
 			},
 		},
 		Filter: ConfigStandardFieldStruct{
-			Field: "test",
+			Value: "$test",
 			Options: []ConfigHeaderStruct{
 				{
 					Name:        "PASS",
@@ -75,7 +75,7 @@ func TestSetHeaderLines(t *testing.T) {
 		},
 		Info: MapConfigInfoFormatStruct{
 			"SVLEN": ConfigInfoFormatStruct{
-				Field:       "test",
+				Value:       "$test",
 				Description: "The length of the SV",
 				Number:      "1",
 				Type:        "Integer",
@@ -83,7 +83,7 @@ func TestSetHeaderLines(t *testing.T) {
 		},
 		Format: MapConfigInfoFormatStruct{
 			"GT": ConfigInfoFormatStruct{
-				Field:       "test",
+				Value:       "$test",
 				Description: "Genotype",
 				Number:      "1",
 				Type:        "String",
@@ -142,7 +142,7 @@ func TestSetHeaderLines(t *testing.T) {
 
 func TestStandardGetValue(t *testing.T) {
 	config := ConfigStandardFieldStruct{
-		Field: "test",
+		Value: "$test",
 	}
 	header := []string{"test", "test2"}
 	values := []string{"value", "I don't want this"}
@@ -161,7 +161,7 @@ func TestStandardGetValue(t *testing.T) {
 	}
 
 	config = ConfigStandardFieldStruct{
-		Field: "2",
+		Value: "$2",
 	}
 	header = []string{"0", "1", "2", "3"}
 	values = []string{"value", "I don't want this", "this is the one", "definitely not this"}
@@ -173,7 +173,7 @@ func TestStandardGetValue(t *testing.T) {
 
 func TestInfoFormatGetValue(t *testing.T) {
 	config := ConfigInfoFormatStruct{
-		Field: "test",
+		Value: "$test",
 	}
 	header := []string{"test", "test2"}
 	values := []string{"value", "I don't want this"}
@@ -192,7 +192,7 @@ func TestInfoFormatGetValue(t *testing.T) {
 	}
 
 	config = ConfigInfoFormatStruct{
-		Field: "2",
+		Value: "$2",
 	}
 	header = []string{"0", "1", "2", "3"}
 	values = []string{"value", "I don't want this", "this is the one", "definitely not this"}
@@ -227,8 +227,8 @@ func TestVariantString(t *testing.T) {
 		},
 	}
 
-	if variant.String() != "chr1\t123\ttest\tA\tC\t100\tPASS\tSVLEN=100\tGT\t0/1\n" {
-		t.Fatalf("Expected variant string to be 'chr1\t123\ttest\tA\tC\t100\tPASS\tSVLEN=100\tGT\t0/1\n', got '%s'", variant.String())
+	if variant.String(1) != "chr1\t123\ttest1\tA\tC\t100\tPASS\tSVLEN=100\tGT\t0/1\n" {
+		t.Fatalf("Expected variant string to be 'chr1\t123\ttest\tA\tC\t100\tPASS\tSVLEN=100\tGT\t0/1\n', got '%s'", variant.String(1))
 	}
 
 	variant = Variant{
@@ -265,8 +265,8 @@ func TestVariantString(t *testing.T) {
 		},
 	}
 
-	if variant.String() != "chr1	123	test	A	C	100	PASS	SVLEN=100;SVTYPE=DEL	GT:CN	0/1:2\n" {
-		t.Fatalf("Expected variant string to be 'chr1	123	test	A	C	100	PASS	SVLEN=100;SVTYPE=DEL	GT:CN	0/1:2\n', got '%s'", variant.String())
+	if variant.String(1) != "chr1	123	test1	A	C	100	PASS	SVLEN=100;SVTYPE=DEL	GT:CN	0/1:2\n" {
+		t.Fatalf("Expected variant string to be 'chr1	123	test	A	C	100	PASS	SVLEN=100;SVTYPE=DEL	GT:CN	0/1:2\n', got '%s'", variant.String(1))
 	}
 
 }
diff --git a/go.mod b/go.mod
index 3b92aa6..4632fb3 100644
--- a/go.mod
+++ b/go.mod
@@ -1,6 +1,6 @@
 module github.com/nvnieuwk/bedgovcf
 
-go 1.20
+go 1.21
 
 require (
 	github.com/urfave/cli/v2 v2.25.7
diff --git a/test_data/big/qdnaseq.yaml b/test_data/big/qdnaseq.yaml
index 2a9d97b..4458795 100644
--- a/test_data/big/qdnaseq.yaml
+++ b/test_data/big/qdnaseq.yaml
@@ -2,16 +2,16 @@ header:
   test:
     value: "test"
 chrom:
-  field: 0
+  value: $0
   prefix: chr
 pos:
-  field: 1
+  value: $1
 id:
   prefix: qdnaseq_
 ref:
   value: N
 alt:
-  value: <CNV>
+  value: ~if $4 < 0 <DEL> <DUP>
   options:
     - name: DEL
       description: Deletion
@@ -26,15 +26,17 @@ filter:
       description: All filters passed
 info:
   cnv_ratio:
-    field: 4
+    value: $4
   end:
-    field: 2
+    value: $2
   svtype:
     value: CNV
   tool:
     value: qdnaseq
+  svlen:
+    value: ~min $2 $1
 format:
   gt:
     value: 0/1
   cn:
-    field: 4
+    value: ~round $4